α-Heterosubstituted Phosphonate Carbanions. 11. Benzoins via an Acyl Anion Equivalent. Novel One-Pot Preparation of Benzofurans via Benzoins Using Hydriodic Acid

Article abstract of DOI:10.1021/jo01308a009

Diethyl 1-(trimethylsiloxy)-1-phenylmethanephosphonate carbanion 2 is introduced as a novel acyl anion equivalent.When 2 reacts with aldehydes or ketones, a 1,4 oxygen-oxygen silicon migration with subsequent loss of diethyl lithium phosphite is observed.An efficient method utilizing 2 for the preparation of otherwise difficultly obtainable substituted benzoins is presented.Also a novel one-pot method which offers a facile entry into the 2-phenylbenzofuran ring system from 2 via benzoin intermediates using hydriodic acid was developed.