CARBONYLATION OF TRICHLOROACETALDEHYDE (CHLORAL) IN CONCENTRATED SULFURIC ACID - STEREOCONTROLLED SYNTHESIS OF CIS- AND TRANS-2,5-BIS(TRICHLOROMETHYL)-1,3-DIOXOLAN-4-ONE

摘要

Carbonylation of trichloroacetaldehyde(chloral) in concentrated sulfuric acid readily gave 2,5-bis(trichloromethyl)-1,3-dioxolan-4-ones (cis and trans) and 3,3,3-trichloro-2-hydroxypropanoic acid. The cis isomer was isolated for the first time, and confirmed by Xray structural analysis. The cis/trans ratio of dioxolanones largely depended upon the concentration of sulfuric acid. Highly diastereoselective formation of the dioxolanones was achieved with 99wt% sulfuric acid (cis : trans = 95 : 5) or with 90wt% sulfuric acid (0 : 100). [References: 19]