GB2035998A - 2-Thioxo-5-thiazolidinones - Google Patents
2-Thioxo-5-thiazolidinones Download PDFInfo
- Publication number
- GB2035998A GB2035998A GB7846469A GB7846469A GB2035998A GB 2035998 A GB2035998 A GB 2035998A GB 7846469 A GB7846469 A GB 7846469A GB 7846469 A GB7846469 A GB 7846469A GB 2035998 A GB2035998 A GB 2035998A
- Authority
- GB
- United Kingdom
- Prior art keywords
- thioxo
- formula
- compound
- thiazolidinone
- salt
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- FDEUSQGAAOSCEA-UHFFFAOYSA-N 2-sulfanylidene-1,3-thiazolidin-5-one Chemical class O=C1CNC(=S)S1 FDEUSQGAAOSCEA-UHFFFAOYSA-N 0.000 title claims abstract description 19
- 150000001875 compounds Chemical class 0.000 claims abstract description 46
- -1 trialkylammonium ion Chemical class 0.000 claims abstract description 43
- 238000000034 method Methods 0.000 claims abstract description 33
- QGJOPFRUJISHPQ-UHFFFAOYSA-N Carbon disulfide Chemical compound S=C=S QGJOPFRUJISHPQ-UHFFFAOYSA-N 0.000 claims abstract description 32
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000007363 ring formation reaction Methods 0.000 claims abstract description 15
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims abstract description 14
- 125000000962 organic group Chemical group 0.000 claims abstract description 14
- 150000003839 salts Chemical class 0.000 claims abstract description 12
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 10
- 125000004432 carbon atom Chemical group C* 0.000 claims abstract description 10
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 10
- 239000001257 hydrogen Substances 0.000 claims abstract description 10
- 229910052783 alkali metal Inorganic materials 0.000 claims abstract description 8
- 150000001340 alkali metals Chemical class 0.000 claims abstract description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims abstract description 5
- 125000005131 dialkylammonium group Chemical group 0.000 claims abstract description 4
- 229910001413 alkali metal ion Inorganic materials 0.000 claims abstract description 3
- 229910001420 alkaline earth metal ion Inorganic materials 0.000 claims abstract description 3
- 125000005210 alkyl ammonium group Chemical group 0.000 claims abstract description 3
- 150000001728 carbonyl compounds Chemical class 0.000 claims abstract description 3
- 125000004433 nitrogen atom Chemical group N* 0.000 claims abstract description 3
- 125000005208 trialkylammonium group Chemical group 0.000 claims abstract description 3
- PNAIPNYVHGAMST-UHFFFAOYSA-N 1-oxo-3,5-dihydro-1,3-thiazol-5-ide-2-thione Chemical compound O=S1[C-]=CNC1=S PNAIPNYVHGAMST-UHFFFAOYSA-N 0.000 claims abstract 6
- DKVNPHBNOWQYFE-UHFFFAOYSA-N carbamodithioic acid Chemical compound NC(S)=S DKVNPHBNOWQYFE-UHFFFAOYSA-N 0.000 claims abstract 2
- 230000003472 neutralizing effect Effects 0.000 claims abstract 2
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 claims abstract 2
- 125000000467 secondary amino group Chemical class [H]N([*:1])[*:2] 0.000 claims abstract 2
- 150000001413 amino acids Chemical class 0.000 claims description 9
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 6
- 239000001117 sulphuric acid Substances 0.000 claims description 6
- 235000011149 sulphuric acid Nutrition 0.000 claims description 6
- 239000002253 acid Substances 0.000 claims description 5
- 125000001797 benzyl group Chemical group [H]C1=C([H])C([H])=C(C([H])=C1[H])C([H])([H])* 0.000 claims description 5
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 claims description 5
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 5
- 108090000765 processed proteins & peptides Proteins 0.000 claims description 5
- 125000001424 substituent group Chemical group 0.000 claims description 5
- 230000002378 acidificating effect Effects 0.000 claims description 4
- 125000000217 alkyl group Chemical group 0.000 claims description 4
- 239000012736 aqueous medium Substances 0.000 claims description 4
- 125000003118 aryl group Chemical group 0.000 claims description 4
- 125000002057 carboxymethyl group Chemical group [H]OC(=O)C([H])([H])[*] 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 239000012990 dithiocarbamate Substances 0.000 claims description 4
- 125000003143 4-hydroxybenzyl group Chemical group [H]C([*])([H])C1=C([H])C([H])=C(O[H])C([H])=C1[H] 0.000 claims description 3
- 150000001412 amines Chemical class 0.000 claims description 3
- 239000012024 dehydrating agents Substances 0.000 claims description 3
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims description 3
- 125000004108 n-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 claims description 3
- 102000004196 processed proteins & peptides Human genes 0.000 claims description 3
- 108010016626 Dipeptides Proteins 0.000 claims description 2
- 108010038807 Oligopeptides Proteins 0.000 claims description 2
- 102000015636 Oligopeptides Human genes 0.000 claims description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical group O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 claims description 2
- 125000004423 acyloxy group Chemical group 0.000 claims description 2
- 239000003513 alkali Substances 0.000 claims description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 2
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 2
- 125000003545 alkoxy group Chemical group 0.000 claims description 2
- 125000002877 alkyl aryl group Chemical group 0.000 claims description 2
- 125000004414 alkyl thio group Chemical group 0.000 claims description 2
- 125000003368 amide group Chemical group 0.000 claims description 2
- 125000000539 amino acid group Chemical group 0.000 claims description 2
- 150000003863 ammonium salts Chemical class 0.000 claims description 2
- 125000003710 aryl alkyl group Chemical group 0.000 claims description 2
- 125000004659 aryl alkyl thio group Chemical group 0.000 claims description 2
- 125000005110 aryl thio group Chemical group 0.000 claims description 2
- 230000006196 deacetylation Effects 0.000 claims description 2
- 238000003381 deacetylation reaction Methods 0.000 claims description 2
- 238000001704 evaporation Methods 0.000 claims description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 2
- 125000004029 hydroxymethyl group Chemical group [H]OC([H])([H])* 0.000 claims description 2
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 claims description 2
- 125000000896 monocarboxylic acid group Chemical group 0.000 claims description 2
- 239000003960 organic solvent Substances 0.000 claims description 2
- 229920001184 polypeptide Polymers 0.000 claims description 2
- 239000002904 solvent Substances 0.000 claims description 2
- 125000000218 acetic acid group Chemical group C(C)(=O)* 0.000 claims 3
- 125000005843 halogen group Chemical group 0.000 claims 1
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 24
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 18
- 239000000243 solution Substances 0.000 description 18
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 12
- 229940024606 amino acid Drugs 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 9
- 235000001014 amino acid Nutrition 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- 238000002360 preparation method Methods 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- DHMQDGOQFOQNFH-UHFFFAOYSA-N Glycine Chemical compound NCC(O)=O DHMQDGOQFOQNFH-UHFFFAOYSA-N 0.000 description 4
- WHUUTDBJXJRKMK-VKHMYHEASA-N L-glutamic acid Chemical compound OC(=O)[C@@H](N)CCC(O)=O WHUUTDBJXJRKMK-VKHMYHEASA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 239000006188 syrup Substances 0.000 description 4
- 235000020357 syrup Nutrition 0.000 description 4
- COLNVLDHVKWLRT-QMMMGPOBSA-N L-phenylalanine Chemical compound OC(=O)[C@@H](N)CC1=CC=CC=C1 COLNVLDHVKWLRT-QMMMGPOBSA-N 0.000 description 3
- 238000013019 agitation Methods 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 239000003208 petroleum Substances 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- 239000004471 Glycine Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- DCXYFEDJOCDNAF-REOHCLBHSA-N L-asparagine Chemical compound OC(=O)[C@@H](N)CC(N)=O DCXYFEDJOCDNAF-REOHCLBHSA-N 0.000 description 2
- ROHFNLRQFUQHCH-YFKPBYRVSA-N L-leucine Chemical compound CC(C)C[C@H](N)C(O)=O ROHFNLRQFUQHCH-YFKPBYRVSA-N 0.000 description 2
- OUYCCCASQSFEME-QMMMGPOBSA-N L-tyrosine Chemical compound OC(=O)[C@@H](N)CC1=CC=C(O)C=C1 OUYCCCASQSFEME-QMMMGPOBSA-N 0.000 description 2
- KZSNJWFQEVHDMF-BYPYZUCNSA-N L-valine Chemical compound CC(C)[C@H](N)C(O)=O KZSNJWFQEVHDMF-BYPYZUCNSA-N 0.000 description 2
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 2
- 125000002777 acetyl group Chemical group [H]C([H])([H])C(*)=O 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229960002989 glutamic acid Drugs 0.000 description 2
- 239000000543 intermediate Substances 0.000 description 2
- 229960005190 phenylalanine Drugs 0.000 description 2
- FSYKKLYZXJSNPZ-UHFFFAOYSA-N sarcosine Chemical compound C[NH2+]CC([O-])=O FSYKKLYZXJSNPZ-UHFFFAOYSA-N 0.000 description 2
- 125000000143 2-carboxyethyl group Chemical group [H]OC(=O)C([H])([H])C([H])([H])* 0.000 description 1
- HBAQYPYDRFILMT-UHFFFAOYSA-N 8-[3-(1-cyclopropylpyrazol-4-yl)-1H-pyrazolo[4,3-d]pyrimidin-5-yl]-3-methyl-3,8-diazabicyclo[3.2.1]octan-2-one Chemical class C1(CC1)N1N=CC(=C1)C1=NNC2=C1N=C(N=C2)N1C2C(N(CC1CC2)C)=O HBAQYPYDRFILMT-UHFFFAOYSA-N 0.000 description 1
- CKLJMWTZIZZHCS-UHFFFAOYSA-N D-OH-Asp Natural products OC(=O)C(N)CC(O)=O CKLJMWTZIZZHCS-UHFFFAOYSA-N 0.000 description 1
- QNAYBMKLOCPYGJ-UHFFFAOYSA-N D-alpha-Ala Natural products CC([NH3+])C([O-])=O QNAYBMKLOCPYGJ-UHFFFAOYSA-N 0.000 description 1
- QNAYBMKLOCPYGJ-UWTATZPHSA-N L-Alanine Natural products C[C@@H](N)C(O)=O QNAYBMKLOCPYGJ-UWTATZPHSA-N 0.000 description 1
- CKLJMWTZIZZHCS-UWTATZPHSA-N L-Aspartic acid Natural products OC(=O)[C@H](N)CC(O)=O CKLJMWTZIZZHCS-UWTATZPHSA-N 0.000 description 1
- QNAYBMKLOCPYGJ-REOHCLBHSA-N L-alanine Chemical compound C[C@H](N)C(O)=O QNAYBMKLOCPYGJ-REOHCLBHSA-N 0.000 description 1
- CKLJMWTZIZZHCS-REOHCLBHSA-N L-aspartic acid Chemical compound OC(=O)[C@@H](N)CC(O)=O CKLJMWTZIZZHCS-REOHCLBHSA-N 0.000 description 1
- LEVWYRKDKASIDU-IMJSIDKUSA-N L-cystine Chemical compound [O-]C(=O)[C@@H]([NH3+])CSSC[C@H]([NH3+])C([O-])=O LEVWYRKDKASIDU-IMJSIDKUSA-N 0.000 description 1
- 239000004158 L-cystine Substances 0.000 description 1
- 235000019393 L-cystine Nutrition 0.000 description 1
- 229930182816 L-glutamine Natural products 0.000 description 1
- AGPKZVBTJJNPAG-WHFBIAKZSA-N L-isoleucine Chemical compound CC[C@H](C)[C@H](N)C(O)=O AGPKZVBTJJNPAG-WHFBIAKZSA-N 0.000 description 1
- 229930182844 L-isoleucine Natural products 0.000 description 1
- 239000004395 L-leucine Substances 0.000 description 1
- 235000019454 L-leucine Nutrition 0.000 description 1
- GLUBLISJVJFHQS-VIFPVBQESA-N Phe-Gly Chemical compound OC(=O)CNC(=O)[C@@H](N)CC1=CC=CC=C1 GLUBLISJVJFHQS-VIFPVBQESA-N 0.000 description 1
- ONIBWKKTOPOVIA-UHFFFAOYSA-N Proline Natural products OC(=O)C1CCCN1 ONIBWKKTOPOVIA-UHFFFAOYSA-N 0.000 description 1
- 108010077895 Sarcosine Proteins 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229960003767 alanine Drugs 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 229960001230 asparagine Drugs 0.000 description 1
- 229960005261 aspartic acid Drugs 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000006071 cream Substances 0.000 description 1
- 229960003067 cystine Drugs 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 150000004659 dithiocarbamates Chemical class 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000004247 glycine and its sodium salt Substances 0.000 description 1
- 235000013905 glycine and its sodium salt Nutrition 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229960000310 isoleucine Drugs 0.000 description 1
- 229960003136 leucine Drugs 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910052757 nitrogen Chemical group 0.000 description 1
- COLNVLDHVKWLRT-UHFFFAOYSA-N phenylalanine Natural products OC(=O)C(N)CC1=CC=CC=C1 COLNVLDHVKWLRT-UHFFFAOYSA-N 0.000 description 1
- 108010036504 phenylalanylglycine Proteins 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 150000003141 primary amines Chemical class 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 229940043230 sarcosine Drugs 0.000 description 1
- 150000003335 secondary amines Chemical class 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229940029258 sodium glycinate Drugs 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- WUWHFEHKUQVYLF-UHFFFAOYSA-M sodium;2-aminoacetate Chemical compound [Na+].NCC([O-])=O WUWHFEHKUQVYLF-UHFFFAOYSA-M 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000012265 solid product Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 125000001984 thiazolidinyl group Chemical group 0.000 description 1
- 229960004441 tyrosine Drugs 0.000 description 1
- 229960004295 valine Drugs 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
- C07D277/02—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings
- C07D277/20—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
- C07D277/02—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings
- C07D277/20—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
- C07D277/32—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D277/36—Sulfur atoms
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D513/00—Heterocyclic compounds containing in the condensed system at least one hetero ring having nitrogen and sulfur atoms as the only ring hetero atoms, not provided for in groups C07D463/00, C07D477/00 or C07D499/00 - C07D507/00
- C07D513/02—Heterocyclic compounds containing in the condensed system at least one hetero ring having nitrogen and sulfur atoms as the only ring hetero atoms, not provided for in groups C07D463/00, C07D477/00 or C07D499/00 - C07D507/00 in which the condensed system contains two hetero rings
- C07D513/04—Ortho-condensed systems
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
Abstract
A method of preparing a 2-thioxo- 5-thiazolidinone of the general formula: <IMAGE> comprises cyclizing a salt of the general formula <IMAGE> A method of preparing a 2-thioxo- 5-thiazolidone of the general formula <IMAGE> comprises cyclizing a salt of the general formula <IMAGE> in the presence of a carbonyl compound of the general formula R4COR5, the cyclization being effected by means of acetic anhydride. In the formulae above, R' represents a hydrogen atom or a monovalent organic group; either R'' and R''' each represents a hydrogen atom or a monovalent organic group or R'' and R''' together with the respective adjacent carbon and nitrogen atoms form an organic ring; and each of @ and @' represents an alkali metal ion or one half of an alkaline earth metal ion, or an ammonium, alkylammonium, dialkylammonium or trialkylammonium ion, each of R4 and R5 represents a hydrogen atom or a monovalent organic group. When R''' is hydrogen an amino compound may be prepared by optionally converting the 2-thioxo-5- thiazolidone to an alkali metal or trialkylammonium salt, reacting the 2- thioxo-5-thiazolidone or the salt thereof with a primary or secondary amine of the formula NHXY to form an amidedithiocarbamate of the formula <IMAGE> where: each of X and Y is hydrogen or a monovalent organic radical (at least one of X and Y not being hydrogen); and @ is an alkali metal or trialkylammonium ion or @HXY; neutralizing the amidedithiocarbamate to convert the amidedithiocarbamate into the corresponding dithiocarbamic acid, which loses carbon disulphide, to leave the amino compound. Some compounds of formula (I) are novel and some compounds of formula (I) may be obtained in optically active forms.
Description
SPECIFICATION 2-Thioxo-5-thiazolidinones
Field of the Invention
The present invention relates to 2-thioxo-5-thiazolidinone and 2-thioxo-5-thiazolidinones substituted at one or both of the 3- and 4-positions.
Background of the Invention
It is well known to produce 2-thioxo-5-thiazolidinone by cyclization under acid conditions of dithiocarbamatoglycinamide, in accordance with the equation:-
4-Alkylidene and 4-arylidene-2-thioxo-5-thiazolidinones are readily prepared from 2-thioxo-5thiazolidinones and some of these have been reduced to the corresponding 4-alkyl or 4-aralkyl-2thioxo-5-thiazolidinones. However, the optically active forms of these substances (which can occur because the 4-position of the thiazolidine ring in them is asymmetric), which would be useful as potential intermediates for the synthesis of peptides, are not accessible by this route.Some of these substances, in optically active forms, have been prepared from the amides of the corresponding aminoacids in a similar reaction to that known for the cyclization of dithiocarbamatoglycinamide previously referred to. However, the overall yields by this method are poor, several steps being involved in the preparation of the substances from the optically active aminoacids.
Description of the Invention
The invention relates, in one aspect, to the preparation of 2-thioxo-5-thiazolidinones optionally substituted at one or both of the 3- and 4-positions.
In accordance with the present invention there is provided a method of preparing a 2-thioxo-5thiazolidinone of the general formula:
comprising cyclizing a salt of the general formula
where:
R" represents a hydrogen atom or a monqvalent organic group;
either R" and R"' each represents a hydrogen atom or a monovalent organic group or R" and R"'
together with the adjacent carbon and nitrogen atom in the thiazolidinone ring form an organic ring fused to the thiazolidinone ring; and
0 0
each of M' and M represents an alkali metal ion or one half of an alkaline earth metal ion, or an ammonium, alkylammonium, dialkylammonium, dialkylammonium or trialkylammonium ion.
Any of R', R" and R"' may be alkyl, aryl, alkaryl or aralkyl and any of R', R" and R"' may be
substituted with one or more substituents, such as alkyl, aryl, hydroxyl, mercapto, amino, amido,
alkylamido, arylamido, carbalkoxy, acyloxy, alkyloxycarbonamide, aryloxycarbonamide,
aralkoxycarbonamide, alkylthio, arylthio, aralkylthio, halogen, and sulphonyl or alkoxy or aroxy.
Where each of R' and R" is an organic group, the compound of formula (I) is a 4-disubstituted-2thioxo-5-thiazolidinone.
Where one of R' and R" is a hydrogen atom and the other is an organic group, the compound of
formula (I) is a 4-monosubstituted-2-thioxo-5-thiazolidinone.
Where R"' is an organic group, the compound of formula (I) is a 3-substituted-2-thioxo-5thiazolidinone.
Where R', R" and R"' are all hydrogen, the compound of formula (I) is 2-thioxo-5-thiazolidinone itself.
The cyclization is preferably effected by means of an acidic dehydrating agent. An intermediate in the reaction of cyclization may be an acid derived from the above-mentioned salts.
If the cyclization is effected by means of a large excess of acetic anhydride, acetyl derivatives of the compounds of formula (I) are produced. These derivatives may be deacylated to give the related compounds of formula (I). The deacetylation may be carried out, for example, by dissolving the acetyl derivative in a solution of an aqueous alkali and then acidifying the solution.
Suitable acidic dehydrating agents are 70 to 80% sulphuric acid and acetic anhydride.
If R', R" and R"' are all hydrogen and a carbonyl compound R4COR5 is present during a cyclization effected by means of acetic anhydride, a 4-substituted-2-thioxo-5-thiazolidinone (it1) is obtained where the 4-substituent is R4R5C=. This provides a novel and extremely convenient method of obtaininq such substances.
In the compound of formula (I), the carbon atom at the 4-position of the thiazolidinone ring is asymmetric if R' and R" are different. Where the carbon atom at the 4-position is asymmetric, the compound of formula (I) may be obtained in optically active forms known as diastereoisomerides or enantiomers.
Where the compound of formula (II) is optically active due to the asymmetry of the carbon atom to which R' and R" are bonded, then the compound of formula (I) may be obtained in an optically active form by cyclization of the compound of formula (II).
The compound of formula (II) may be prepared by known methods, by reacting carbon disulphide with an alkali metal or alkaline earth metal or ammonium or substituted ammonium salt of an a-amino acid, the amino acid having the formula R'R"C(NHR"')COOH, where R', R" and R"' are as specified above. This reaction is preferably carried out in an aqueous medium. The aqueous medium preferably comprises an organic solvent in which carbon disulphide is soluble.
The compounds of formula (II) may be isolated by evaporating off solvent from the solution in which they are prepared.
I have found that compounds of formula (II) are usually thick gums and few of them crystallize easily. Some of the free dithiocarbamic acids derived from them are crystalline solids which are, however, unstable at room temperature.
If the a-amino acid is optically active due to the asymmetry of the carbon atom to which R' and
R" are attached, then the compound of formula (II) obtained from the amino acid is optically active.
Hence optically active compounds of formula (I) may be prepared from optically active a-amino acids.
The compound of formula (II) may contain unevaporated water derived from its preparation when subjected to the cyclization reaction to produce the compound of formula (I).
I have found that in carrying out the method of the invention, using 75% sulphuric acid to effect the cyclization of the compound of formula (II), yields of greater than 50% of 4-alkyl and 4-aralkyl-2thioxo-5-thiazolidinones may be obtained.
I have found that 4-monosubstituted-2-thioxo-5-thiazolidinones are, in general, highly crystalline compounds which are stable for long periods of time, and which produce polymeric products when heated above 1 400C. They are readily soluble in alkaline solutions presumably because (when R"' is hydrogen) of the acidity of the enthiol polymerization possibly at the 2:3 positions. They, or their alkali metal or trialkylammonium salts, react rapidly with primary and secondary amines with opening of the thiazolidinone ring and formation of the amide-dithiocarbamate
0+ where B is an alkali metal or trialkylammonium ion or the ion NHXY, and NHXY is the amine reactant.
Upon neutralization, these dithiocarbamate salts are converted into the corresponding dithiocarbamic acids, which lose carbon disulphide to leave the corresponding amino compound. Where the substance
NHXY is the salt of an amino acid the product is a dipeptide and where NHXY is an oligo- or polypeptide the product is a peptide having one more aminoacid residue than the amine NHXY.
The following 4-monosubstituted-2-thioxo-5-thiazolidinones have been prepared by the method of the invention, starting from an a-amino acid.
ILt, Substituent at m.p. initial if relevant
4-position (0C) aminoacid (in ethanol)
methyl 128 L-alanine +20.5 ethyl 84 DL-a-aminobutyric acid
1-propyl 86 DL-a-aminopentanoic
acid 2-propyl 103 L-valine --13.50 1 -butyl 74 DL-a-aminohexanoic acid 2-butyl 88 L-isoleucine 44.80 2-methyl-1-propyl 170 L-leucine +7.10 benzyl 165 L-phenylalanine -9.1" p-hydroxybenzyl 215 dec L-tyrosine -24.7" 2-methylthioethyl 80 L-methionine O carboxymethyl 1 60 dec L-aspartic acid -1.00 2-carboxyethyl 1 52-4 dec L-glutamic acid -1 .3 0 carboxamidomethyl darkens L-asparagine
at 200 2-carboxamidoethyl 1 23 dec L-glutamine 2-methoxycarbonylethyl 92 dec L-y-methyl glutamate
The following other 2-thioxo-5-thiazolidinones have also been prepared by the methods of the invention, starting from an a-amino acid.
[ai2O initial if relevant
compound m.p. amino-acid (in methanol) 2-thioxo-5-thiazolidinone blackens > 1 600C glycine 3-methyl-2-thioxo-5- 840C sarcosine
thiazolidinone
Octahydro-2-thioxo-pyrrolo- 620C dec proline
[1,2-c]-thiazol-8-one
Di(5-oxo-2-thioxothiazolidin- 1 460C L-cystine
4)-ylmethyl disulphide
The invention further relates, in another aspect, to novel compounds.
In accordance with the present invention, there are provided compounds of the general formula (I) given above, such compounds excluding 4-monosubstituted-2-thioxo-5-thiazolidinones which are unsubstituted at the 3-position and where the 4-substituent is benzyl, oxindolyl 3-hydroxyoxindolyl, ethyl, p-hydroxybenzyl, methyl, isobutyl, 2-(methylthio)-ethyl, 2-(aminocarbonyl)-ethyl, isopropyl, 1 - butyl, hydroxymethyl or carboxymethyl.
Such novel compounds include:
2-thioxo-5-thiazolidinones having a ring fused with side c (i.e. the side containing the 3 and 4carbon atoms) of the thiazolidinone ring.
In particular such novel compounds include:
4-(1 -propyl)-2-thioxo-5-thiazolidinone
4-(2-butyl)-2-thioxo-5-thiazolidinone
4-(2-carboxyethyl)-2-thioxo-5-thiazolidinone
4-aminocarbonyl methyl-2-thioxo-5-thiazol idinone
4-(2-methoxycarbonylethyl)-2-thioxo-5-thiazolidinone Octahydro-2-thioxo-pyrrolo-[1 ,2-c]-thiazol-8-one Di(5-oxo-2-thioxothiazolidin-4)ylmethyldisulphide.
According to a preferred feature of the invention, there are provided novel compounds as specified above and wherein the carbon atom in the 4-position in the thiazolidinone ring is asymmetric, each such compound being in one of its diastereoisomeric (or enantiomeric) forms and substantially free of its other diastereoisomeric form. The invention also provides 2-thioxo-5-thiazolidinones in one of their diastereoisomeric (or enantiomeric) forms and substantially free of their other diastereoisomeric forms where the substituent on the 4-position is methyl, benzyl, isobutyl, 2methylthioethyl, carboxymethyl and 2-(aminocarbonyl)ethyl.
The method of the invention is illustrated by the following examples.
Example 1
Preparation of L-4-benzyl-2-thioxo-5-thiazolidinone
L-Phenylalanine (16 g.) was dissolved in an aqueous solution of sodium hydroxide (4 g) in water (50 ml). To the solution was added a solution of carbon disulphide (5 g) in methanol (50 ml), and the solution was well stirred. After 10 minutes a substantial separation of phenylalanine had occurred. An aqueous solution of sodium hydroxide (2 g) in water (50 ml) was added, followed by a solution of carbon disulphide (2.5 g) in ethanol (25 ml). Stirring was continued. After 10 minutes, an aqueous solution of sodium hydroxide (1 g) in water (12.5 ml) was added, followed by a solution of carbon disulphide (1.25 g) in ethanol (12.5 ml). Ten minutes later, a further amount of sodium hydroxide (1 g) dissolved in water (12.5 ml) was added, followed by a solution of carbon disulphide (1.25 g) in ethanol (12.5 ml).After ten minutes' stirring, the solution was pale yellow, with a small amount of unreacted carbon disulphide. This solution was evaporated in vacuo to a thick syrup which was poured in a thin stream into a cooled mixture of sulphuric acid (150 ml, d- 1.78) and water (50 ml) with vigorous agitation. After 5 minutes the mixture was poured onto ice. One hour later, the L-4-benzyl-2-thioxo-5thiazolidinone was filtered off and recrystallized from ether as glistening cream coloured short needles, m.p. 1 650 decomp., [aj200.1 0 (7.6 g). A second crop (5.8 g, m.p. 1620 decomp.) was obtained by dilution of the ethereal filtrate with light petroleum.The substance had ultraviolet absorption peaks at 245 and 282 my. When the substance was treated in methanol with equimolar amounts of sodium hydroxide and sodium glycinate, the solution evaporated to small volume and neutralized with two moles of hydrochloric acid under a layer of ethyl acetate, the ethyl acetate removed, the water layer evaporated to dryness and the residue recrystallized from water, a yield of 61% of the theoretical quantity of L-phenylalanyl-glycine, ta]20+ 14.2, was obtained.
Example 2
Preparation of 2-thioxo-5-thiazolidinone
Glycine (7.5 g) was dissolved in a solution of sodium hydroxide (4 g) in water (25 ml). A solution of carbon disulphide (5 g) in methanol (50 ml) was added with stirring and solutions of carbon disulphide (5 g) in methanol (50 ml) and of sodium hydroxide (4 g) in water (25 ml) were added during a period of 30 minutes with vigorous stirring. The product was evaporated to a thick syrup under reduced pressure. The syrup was poured in a thin stream into a cooled mixture of sulphuric acid (d=1.84) (150 ml) and water (50 ml) with vigorous agitation. Two minutes after the last addition, the mixture was poured on ice and, after 30 min, 2-thioxo-5-thiazolidinone was filtered off. It was dissolved in ethyl acetate, the solution was dried over anhydrous sodium sulphate and the product (8.2 g) obtained as elongated p!ates by adding light petroleum.
Example 3
Preparation of 4-(2-methoxyca rbonyl)-2-thioxo-5-thiazol idinone
To a well-stirred suspension of the y-methyl ester of L-glutamic acid (8.75 g) in methanol (100 ml) containing carbon disulphide (10 ml) was added, during 30 min, a solution of sodium hydroxide (4 g) in water (50 ml). The pale yellow solution was evaporated under reduced pressure to leave a pale yellow syrup. This was added dropwise to 75% sulphuric acid at room temperature with vigorous agitation. The product was poured on ice and after 30 minutes the solid product was filtered off. It was recrystallized from ether-light petroleum as prismatic needles, m.p. 920 decomp (5.4 g).
Claims (32)
1. A method of preparing a 2-thioxo-5-thiazolidinone of the general formula:
comprising cyclizing a salt of the general formula
where:
R' represents a hydrogen atom or a monovalent organic group;
either R" and R"' each represents a hydrogen atom or a monovalent organic group or R" and R"' together with the respective adjacent carbon and nitrogen atoms form an organic ring; and 00 each of M and M' represents an alkali metal ion or one half of an alkaline earth metal ion, or an ammonium, alkylammonium, dialkylammonium; or trialkylammonium ion.
2. A method according to claim 1, wherein any of R', R" and R"' is an alkyl, aryl, alkaryl or aralkyl group and is substituted or unsubstituted.
3. A method according to claim 2, wherein any of R', R" and R"' is substituted with one or more substituents selected from alkyl, aryl, hydroxyl, mercapto, amino, amido, alkylamido, arylamido, carbalkoxy, acyloxy, alkyloxycarbonamide, aryloxycarbonylamide, aralkyloxycarbonamide, alkylthio, arylthio, aralkylthio, sulphonyl, alkoxy and aroxy groups and halogen atoms.
4. A method according to any preceding claim, wherein each of R' and R" is an organic group, the
compound of formula (I) being a 4-disubstituted-2-thioxo-5-thiazolidinone.
5. A method according to any preceding claim, wherein one of R' and R" is a hydrogen atom and
the other is an organic group, the compound of formula (I) being a 4-monosubstituted-2-thioxo-5
thiazolidinone.
6. A method according to any preceding claim, wherein R"' is an organic group, the compound of formula (I) being a 3-substituted-2-thioxo-5-thiazolidinone.
7. A method according to claim 1, wherein R', R" and R"' are all hydrogen, the compound of
formula (I) being 2-thioxo-5-thiazolidinone itself.
8. A method according to any preceding claim, wherein the cyclization is effected by means of an
acidic dehydrating agent.
9. A method according to claim 8, wherein an intermediate in the cyclization reaction is an acid
derived from the salt of formula (II).
1 0. A method according to claim 8 or 9, wherein the acidic dehydrating agent is 70 to 80%
sulphuric acid or acetic anhydride.
11. A method according to any preceding claim, wherein the cyclization is effected by means of a
large excess of acetic anhydride, an acetyl derivatives of the compound of formula (I) being produced
and the acetyl derivatives being deacylated to give the compound of formula (I).
12. A method according to claim 11, wherein the deacetylation is carried out by dissolving the
acetyl derivative in a solution of an aqueous alkali and then acidifying the solution.
13. A method according to any preceding claim, wherein the compound of formula (II) is optically
active due to the asymmetry of the carbon atom to which R' and R" are bonded and the compound of formula (I) is obtained in an optically active form by cyclization of the compound of formula (II).
1 4. A method of preparing a 2-thioxo-5-thiazolidone of the general formula
comprising cyclizing a salt of the general formula
in the presence of a carbonyl compound of the general formula R4CORs, the cyclization being effected
by means of acetic anhydride, 0 0 where: each of M and M' is as specified in claim 1; and each of R4 and R5 represents a hydrogen
atom or a monovalent organic group.
1 5. A method according to any preceding claim, wherein the compound of formula (II) is prepared
by reacting carbon disulphide with an alkali metal or alkaline earth metal or ammonium or substituted
ammonium salt of an a-amino acid, the amino acid having the formula R'R"C(NHR"')COOH, where R', R" and R"' are as specified in claim 1.
1 6. A method according to claim 15, wherein the reaction of carbon disulphide with the salt of an
a-amino acid is carried out in an aqueous medium.
1 7. A method according to claim 15, wherein the aqueous medium comprises an organic solvent
in which carbon disulphide is soluble.
18. A method according to claim 1 6 or 1 7, wherein the compound of formula (II) is isolated by
evaporating off solvent from a solution in which it is prepared.
19. A process of preparing an amino compound, comprising the method of any preceding claim, (when P"' is hydrogen) optionally converting the 2-thioxo-5-thiazolidone formed by said method to an alkali metal or trialkylammonium salt, reacting the 2-thioxo-5-thiazolidone or the salt thereof with a primary or secondary amine of the formula NHXY to form an amide-dithiocarbamate of the formula
where:
each of X and Y is hydrogen or a monovalent organic radical (at least one of X and Y not being hydrogen); and
0 0+ B is an alkali metal or trialkylammonium ion or NHXY;
neutralizing the amide-dithiocarbamate to convert the amide-dithiocarbamate into the corresponding dithiocarbamic acid, which loses carbon disulphide, to leave the amino compound.
20. A process according to claim 19, wherein the compound of formula NHXY is the salt of an amino acid, the amino compound produced being a dipeptide.
21. A process according to claim 1 9, wherein the compound of formula NHXY is an oligo- or polypeptide, the amino compound produced being a peptide having one more amino-acid residue than the amine NHXY.
22. A compound of the general formula (I) given in claim 1, where the 4-substituent is benzyl, oxindolyl 3-hydroxyoxindolyl, ethyl, p-hydroxybenzyl, methyl, isobutyl, 2-(methylthio)ethyl, 2- (aminocarbonyl)-ethyl, isopropyl, 1 -butyl, hydroxymethyl or carboxymethyl and not being a 4monosubstituted-2-thioxo-5-thiazolidinone unsubstituted at the 3-position.
23. A 2-thioxo-5-thiazolidinone having a ring fused with side c (i.e. the side containing the 3- and 4-carbon atoms) of the thiazolidinone ring.
24. 4-( 1 propyl)-2-thioxo-5-thiazolidinone.
25. 4-(2-butyl)-2-thioxo-5-thiazolidinone.
26. 4-(2-carboxyethyl)-2-thioxo-5-thiazolidinone.
27. 4-aminocarbonylmethyl-2-thioxo-5-thiazolidinone.
28. 4-(2-methoxycarbonylethyl)-2-thioxo-5-thiazolidinone.
29. Octahydro-2-thioxo-pyrrolo-[1,2-c]-thiazol-8-one.
30. Di(5-oxo-2-thioxothiazolidin-4)xylmethyl disulphide.
31. A compound according to any of claims 22 to 30, wherein the carbon atom in the 4-position in the thiazolidinone ring is asymmetric, the compound being in one of its diastereoisomeric (or enantiomeric) forms and substantially free of its other diastereoisomeric form.
32. A 2-thioxo-5-thiazoiidinone in one of its diastereoisomeric (or enantiomeric) forms and substantially free of their other diastereoisomeric forms where the substituent at the 4-position is methyl, benzyl, isobutyl, 2-methylthioethyl, carboxymethyl or 2-(aminocarbonyl)ethyl.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7846469A GB2035998B (en) | 1978-11-29 | 1978-11-29 | 2-thioxo-5-thiazolidinones |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7846469A GB2035998B (en) | 1978-11-29 | 1978-11-29 | 2-thioxo-5-thiazolidinones |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2035998A true GB2035998A (en) | 1980-06-25 |
| GB2035998B GB2035998B (en) | 1983-05-05 |
Family
ID=10501393
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7846469A Expired GB2035998B (en) | 1978-11-29 | 1978-11-29 | 2-thioxo-5-thiazolidinones |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2035998B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0047109A1 (en) * | 1980-08-22 | 1982-03-10 | Ono Pharmaceutical Co., Ltd. | Rhodanine derivatives, process for their preparation, and aldose reductase inhibitor containing the rhodanine derivatives as active ingredient |
| FR2751327A1 (en) * | 1996-07-22 | 1998-01-23 | Rhone Poulenc Agrochimie | INTERMEDIATES FOR THE PREPARATION OF 2-IMIDAZOLINE-5-ONES |
-
1978
- 1978-11-29 GB GB7846469A patent/GB2035998B/en not_active Expired
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0047109A1 (en) * | 1980-08-22 | 1982-03-10 | Ono Pharmaceutical Co., Ltd. | Rhodanine derivatives, process for their preparation, and aldose reductase inhibitor containing the rhodanine derivatives as active ingredient |
| FR2751327A1 (en) * | 1996-07-22 | 1998-01-23 | Rhone Poulenc Agrochimie | INTERMEDIATES FOR THE PREPARATION OF 2-IMIDAZOLINE-5-ONES |
| WO1998003490A1 (en) * | 1996-07-22 | 1998-01-29 | Rhone Poulenc Agro | Intermediates for the preparation of 2-imidazoline-5-ones |
| EA001518B1 (en) * | 1996-07-22 | 2001-04-23 | Рон-Пуленк Агро | Intermediates for the preparation of 2-imidazoline-5-ones |
| CN1072651C (en) * | 1996-07-22 | 2001-10-10 | 罗纳-普朗克农业公司 | Intermediates for the preparation of 2-imidazolin-5-one |
| US6320057B1 (en) | 1996-07-22 | 2001-11-20 | Rhone Poulenc Agro | Intermediates for the preparation of 2-imidazoline-5-ones |
| US6570021B2 (en) | 1996-07-22 | 2003-05-27 | Rhone-Poulenc Agro | Intermediates for the preparation of 2-imidazolin-5-ones |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2035998B (en) | 1983-05-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| SU850001A3 (en) | Method of preparing proline derivatives | |
| JP5813647B2 (en) | Synthetic methods such as ergothioneine | |
| KR900008012B1 (en) | α-L-aspartyl-L-phenylalanine methyl ester and its hydrochloride method | |
| CZ297631B6 (en) | Process for preparing (S) - (+) - 3- (aminomethyl) -5-methylhexanoic acid and intermediates useful in this preparation | |
| US3979449A (en) | Preparation of an asparagine or a glutamine | |
| DK159680B (en) | CYCLIC IMIDES USED FOR THE PREPARATION OF CYCLIC AMINO ACIDS | |
| JPH0655757B2 (en) | Process for producing N-alkylated dipeptides and their esters | |
| US4136101A (en) | Process for preparing dialkyl (p-aminobenzoyl) glutamates | |
| US3184505A (en) | Process for the n-monoacylation of cysteine | |
| EP0592643B1 (en) | Pleuromutilin derivatives | |
| US4720554A (en) | Aromatic sulfonic acid salts of a proline derivative | |
| SU747419A3 (en) | Method of producing derivatives of amino acids or their salts or optical isomers | |
| US4918224A (en) | Method of preparing salts of N-acetyl cysteine or N-acetyl homocysteine | |
| GB2035998A (en) | 2-Thioxo-5-thiazolidinones | |
| BR0013750B1 (en) | INTERMEDIARIES FOR THE PRODUCTION OF NAPHTHRIDINE-3-CARBOXYLIC ACID DERIVATIVES | |
| RU2548153C2 (en) | Method for synthesis of 2-thiohistidine and analogues thereof | |
| US3741948A (en) | Process for the preparation of n-protected - alpha - l-glutamyl - s -benzyl-l-cysteinylglysines | |
| SU803859A3 (en) | Method of preparing omega-thiopropionamides or their acid-additive salts | |
| Yuki et al. | Studies on Antiviral Agents. III. Synthesis of Tenuazonic Acid Derivatives. | |
| US4411836A (en) | Racemization of an α-methyl-β-acylthiopropionic acid | |
| HUP0201262A2 (en) | Process for preparing [s-(r*,s*)]-betha-[[[1-[1-oxo-3-(4-piperidinyl)propyl]-3-piperidinyl]carbonyl]amino]-3-pyridinepropanoic acid and derivatives | |
| US6291710B1 (en) | Process for preparing sulfonyl halides | |
| JPH078855B2 (en) | Sulfonium compound | |
| EP0437566B1 (en) | Phenyl-glycine derivatives | |
| Savard et al. | SYNTHESIS OF A NEW α-AMINO ACID, S-METHYL-β, β-DIMETHYLCYSTEINE |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |