Process for producing pyridine derivatives

Compounds of formula where X and Y, which may be the same or different, are carboxyl, alkoxycarbonyl, aldehyde, hydroxymethyl or halogeno-methyl radicals, are prepared by reacting a compound of formula X1CH = CHY1 where X1 and Y1 are the same as X and Y or together represents a carboxylic acid anhydride radical, with a compound of formula where R is a hydrocarbon residue having 1 to 7 carbon atoms, and subsequently desulphurizing, e.g. by heating in the presence of a strong acid. When X and Y are not hydroxymethyl radicals the products may be converted to pyridoxin by hydrolysis or reduction. In examples, 4-methyl-5-ethoxythiazole is reacted with diethyl maleate, diethyl fumarate, maleic acid anhydride and butene diol.