REACTIONS OF ELECTROCHEMICALLY GENERATED ORGANOMETALICS .4. SYNTHESIS OF ALPHA,ALPHA,BETA,BETA-TETRASUBSTITUTED BETA-LACTONES FROM KETONES, ETHYL ALPHA-BROMOISOBUTYRATE AND INDIUM OR ZINC - FACTORS INFLUENCING THE BETA-LACTONE FORMATION IN THE ELECTROCHEMICAL AND THE CLASSICAL PROCEDURE OF THE REFORMATSKY REACTION

An efficient synthesis of alpha,alpha,beta,beta-tetrasubstituted beta-lactones is achieved by an electrochemically supported Reformatsky reaction of aliphatic and aromatic ketones with ethyl alpha-bromoisobutyrate at a sacrificial indium anode. Under these conditions, in most cases the expected beta-hydroxy esters are formed only in negligible amounts or not at all. beta-Lactones are also obtained with a sacrificial zinc anode or even with indium or zinc powder. The substitution pattern of the reactants, the polarity of the solvent, and the applied metal are recognized as factors influencing the extent of the beta-lactone formation.