The reaction between triphenylphosphine and methyl 2-bromoalkanoates

Abstract

Because of the versatile applications of the Wittig reaction, the Touer (1-nethoxycarbonylalkvl)triphenylphosphonium bromides 1 (R * H, Ne) are uell characterized, useful synthetic intermediates. The higher members of the series, however, have I not been isolated, with the exception of ethyl esters 1 (R * Et or n-Bu, ethyl esters instead of methyl esters)1, 2. On the other hand, the obvious preparation of salts 1, namely the reaction between triphenylphosphine 2 and a methyl 2-bromoalkanoate 3, has not been the subject of a systematic study, although it can be concluded from literature data that vigorous reaction conditions and/or long reaction times are needed for the preparation of the higher members of the series 3. Finally, it is also known that several salts of type 1 (R - H, Ph, Ac) can decompose thermally 4.5, givlng methyl bromide, carbon dioxide, ylid 6 and salt 7 (Scheme)