Novel Cyclodehydration Reaction of Hydroxyphenols. An Alternative to the Mitsunobu Reaction.

A mild, efficient and stereospecific intramolecular process for converting hydroxyphenols into benzodioxanes, dihydrobenzopyrans and dihydrobenzofurans via imidate esters is described. The only by-products are N,N-dimethylformamide and triethylamine hydrochloride which are removed by aqueous work-up making this process highly amenable to large scale operation.