N to C Aryl Migration in Lithiated Carbamates: alpha-Arylation of Benzylic Alcohols

• Published in: Journal of the American Chemical Society
• Main Authors: Clayden, J, Farnaby, W, Grainger, D M, Hennecke, U, Mancinelli, M, Tetlow, D J, Hillier, I H, Vincent, M A
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2009
• Subjects: metalated nitrogen derivatives; electrophilic substitution; enantioselective synthesis; organozinc addition; tertiary alcohols; organic-synthesis; carbonic-acid; ketones; rearrangement; diarylmethylamines; Carbonic acid
• Online Access: https://research.manchester.ac.uk/en/publications/4867edee-793a-4090-acb0-15083fa1be2c; https://doi.org/Doi 10.1021/Ja808959e

We report a new mode of reactivity displayed by lithiated O-benzyl carbamates carrying an N-aryl substituent: upon lithiation, the N-aryl group is transferred cleanly from N to C. An arylation of the carbamate results, providing a route to alpha,alpha-arylated secondary or tertiary alcohols. We also report density functional theory calculations supporting the proposal that arylation proceeds through a dearomatizing attack on the aromatic ring, a significantly lower energy pathway than the 1,2-acyl transfer observed with related N-alkyl carbamates.