The Base-catalyzed Condensation of α-Haloaldehydes with Dichloroacetates

Abstract
The reaction of aliphatic α-haloaldehydes with methyl dichloroacetate in the presence of sodium methoxide was carried out. α-Chloroaldehydes afforded 2,4-dichloro-2,3-epoxyalkanoates (5), whereas α-bromoaldehydes gave 2,2-dichloro-3,4-epoxyalkanoate (7). The attempted epoxy-carbonyl rearrangement of 5 with hydrogen chloride or thionyl chloride failed. The thermal decomposition of methyl 2,4-dichloro-2,3-epoxynonanoate (5c) at 300–400°C afforded methyl 3-chloro-2-oxo-3-nonenoate (9c), and the similar treatment of methyl 2,4-dichloro-4-methyl-2,3-epoxypentanoate (5a) afforded a mixture of methyl 3,4-dichloro-4-methyl-2-oxopentanoate (6a), methyl 3-chloro-4-methyl-2-oxo-3-pentenoate (9a), and methyl 3-chloro-4-methyl-2-oxo-4-pentenoate (10). The treatment of 5 with thiourea in methanol gave the thiazole derivative (15), but neither sodiomalonate nor sodioacetoacetate reacted with 5.

This publication has 5 references indexed in Scilit: