GB823068A - Condensation products from glucosides - Google Patents

Abstract

The invention comprises compounds of the formula <FORM:0823068/IV (a)/1> (R1 represents H or an alkyl group containing from 1-6 carbon atoms, and R2 denotes alkyl, aryl, or a heterocyclic residue), and their preparation by condensing the corresponding glucoside with an aldehyde R2CHO, preferably in the presence of a water-binding agent, particularly zinc chloride, anhydrous copper sulphate, or small quantities of concentrated sulphuric or hydrochloric acid, or p-toluene sulphonic acid. An inert solvent, e.g. dioxane or dimethylformamide may be used and the water produced in the reaction removed by azeotropic distillation with an immiscible solvent. In examples: (1) podophyllotoxin glucoside is shaken with benzaldehyde and fused zinc chloride, excess aldehyde distilled off the residue treated with aqueous chloroform, the organic layer separated, dried and distilled, yielding podophyllotoxin-benzylidine glucoside, purified by crystallization from ethanol; similarly (2) to (4) and (6) to (13), are prepared the p-methoxy - benzylidene-, p - methylbenzylidene-, thenylidene-, ethylidene- and salicylidene-derivatives of podophyllotoxin glucoside; the benzylidene-derivatives of a - and b -peltatin glucosides and of 41-demethyl-41-ethylpodophyllotoxin glucoside; and the benzylidene, anisylidene- and thenylidene derivatives of 41 - demethyl - podophyllotoxin glucoside; (5) podophyllotoxin glucoside is refluxed in anhydrous furfural containing a little nitric acid under reduced pressure and excess furfural removed, yielding furfurylidene glucoside, purified by crystallization from ethanol. Specifications 768,919, 777,662 and 777,900 are referred to.