Reactions of formaldehyde with methylene compounds. Part I. Products from acetoacetic esters

Abstract

We have prepared the ethyl and methyl esters of 2,2-di(hydroxymethyl)acetoacetic acid (I) and 2,6-dihydroxy-2,6-dimethyl-3,7-dioxabicyclo[3,3,1]nonane-1,5-dicarboxylic acid (X). The esters of the former, though impure, afford normal diacetates with acetic anhydride–pyridine, but with acetyl chloride the ethyl ester gives a 1,3-dioxan (Va), and with ammonia, a dihydropyridine (VIa). With piperidine, both esters (I) afford unsaturated esters (VII), by a C→O-acetyl transfer reaction. The methyl ester (VIIb) has also been obtained from the methyl ester (Xb) with piperidine and paraformaldehyde.

Under acid conditions, the esters (X) lose water to give tricyclic compounds (XIIIa and b), which can be hydrolysed to the half esters and to the di-acid. Acetylation of the esters (X) with acetic anhydride gives monoacetates.