Tertiary alcohols by tandem β-carbolithiation and N→C aryl migration in enol carbamates

Enol carbamates (O-vinylcarbamates) derived from aromatic or α,β-unsaturated compounds and bearing an N-aryl substituent undergo carbolithiation by nucleophilic attack at the (nominally nucleophilic) β position of the enol double bond. The resulting carbamate-stabilized allylic, propargylic, or benzylic organolithium rearranges with N→C migration of the N-aryl substituent, creating a quaternary carbon α to O. The products may be readily hydrolyzed to yield multiply branched tertiary alcohols in a one-pot tandem reaction, effectively a polarity-reversed nucleophilic β-alkylation-electrophilic α-arylation of an enol equivalent. © 2011 American Chemical Society.