GB798318A - Improvements in or relating to furan compounds and the manufacture thereof - Google Patents

Abstract

The invention comprises (1) compounds of the formula <FORM:0798318/IV (b)/1> where R is hydrogen or acyl and R1 is hydrogen, alkyl or cycloalkyl (provided that when R1 is hydrogen R is also hydrogen), and their acid addition salts; (2) the production thereof by reacting a 2-(a -acylamino-ethyl)-furan with an acetylene dicarboxylic ester, hydrogenating the product to give <FORM:0798318/IV (b)/2> (Z=R, Y=R1) and pyrolysing the latter to split off ethylene; if desired the groups R and R1 may be hydrolysed; (3) the production of compounds of the formula <FORM:0798318/IV (b)/3> (A=H or acyl) from compounds of the first formula above in various ways, viz: (a) 2-(a -acylamino - ethyl) - 3 : 4 - bis - (hydroxymethyl)-furan by direct selective reduction (e.g. with lithium aluminium hydride); (b) 2-(a -acylamino - ethyl) - 3 : 4 - bis - (acyloxymethyl) - furan by hydrolysis of R and R1 to H, reesterification and selective reduction in the presence of an acid anhydride or with subsequent acylation. The acylamino group may be subsequently hydrolysed to amino. The acyl group is preferably aliphatic of 1-8 carbon atoms but may also be aroyl, aralkanoyl or cycloalkanoyl, suitable groups of these types being mentioned. The esterifying group is preferably C1-C8 alkyl but may also be cyclopentyl or cyclohexyl. The 3 : 4-bis-acyloxymethyl compounds can be converted into pyridoxin as in Specification 798,320. In the examples: (1) 2-(a -acetylamino-ethyl)-furan is converted to 2-(a -acetylamino-ethyl)-3 : 4-dicarbethoxy-furan, with or without isolation of the intermediates diethyl 3 : 6-endoxo-3-(a -acetylamino - ethyl) - 3 : 6 - dihydrophthalate and -3 : 4 : 5 : 6-tetrahydrophthalate; (2) the product of (1) is reduced to 2-(a -acetylaminoethyl) - 3 : 4 - bis - (acetoxymethyl) - furan; (3) the product of (1) is hydrolysed to 2-(a -aminoethyl) - 3 : 4 - dicarboxy - furan (hydrochloride described), the latter esterified with methanol (via hydrochloride of ester) and treated successively with lithium aluminium hydride and acetic anhydride to give 2-(a -acetylaminoethyl) - 3 : 4 - bis - (acetoxymethyl) - furan; (4) the last-named is hydrolysed to 2-(a -aminoethyl) - 3 : 4 - bis - (hydroxymethyl) - furan and oxidised with chlorine to give pyridoxin hydrochloride. Alternative reactants and the corresponding intermediates are mentioned.