Methyl 2,3-dibromo-2,3-diarylpropanoates. Debromination and dehydrobromination reactions

Abstract

Rate and product studies of the iodide- and methoxide-mediated reactions of methyl (R,R)- and (R,S)-2,3-dibromo-2,3-diarylpropanoates and some of their 2- and 3-(4-substitutedphenyl)-derivatives have been carried out. The results indicate that the reaction of iodide with most of the substrates affords only debrominated olefins, whereas the course of the methoxide-promoted reactions seems to depend mainly on the configuration of the starting substrate. Thus, in the eliminations induced by methoxide ion most of the (R,R)-compounds led exclusively to dehydrobrominated olefins. On the other hand, the dehydrobrominations of most of the (R,S)-isomers can be accompanied by debromination. Mechanistic aspects are discussed.