ChemInform Abstract: A Facile Method for Synthesis of Three Carbon-Homologated Carboxylic Acid by Regioselective Ring-Opening of β-Propiolactones with Organocopper Reagents.

ChemInform Abstract

Organocopper reagents, such as diorganocuprates (e.g. (II), (VIII)), organocopper-tributylphosphine (e.g. (IV)) and Grignard reagents (e.g. (V)) in the presence of a Cu(I) salt, react with β-propiolactone (I) by regioselective β-carbon fission to give 3-substituted propionic acids such as (III). The acids (VI) are prepared similarly. Among the three organocopper reagents, diorganocuprate, especially halomagnesiumcuprate (e.g. (II), (VIII)) give the highest yields of the acids, and remarkably, this is observed in the ring-opening of sterically hindered β-propiolactones such as (VII) or (X). The ring-opening is confirmed to proceed via an SN₂ pathway by an investigation of the stereochemistry of the reaction of a cis/trans mixture of the dimethylpropiolactone (X) with (VIII).