A New Synthesis of Phthalides by Internal Trapping in Ortho-Lithiated Carbamates Derived from Benzylic Alcohols

Article abstract of DOI:10.1021/jo00033a024

The addition of t-BuLi to a low-temperature THF solution of o-bromocarbamates 2 leads to ortho-lithiated intermediates 3, in which internal trapping by the electrophile on the side chain then takes place.This novel Parham-type anionic cyclization procedure affords the variously substituted phthalides 5 in high yields and can also be used for the preparation of lactones 8, which are useful for the synthesis of aristocularine alkaloids.