Lewis Acid-Catalyzed Direct Amination of Benzhydryl Alcohols
作者:Vincent Terrasson、Sylvain Marque、Marie Georgy、Jean-Marc Campagne、Damien Prim
DOI:10.1002/adsc.200600236
日期:2006.10
The Lewis acid-mediated directamination of benzylic alcohols is described, providing various benzylic amine derivatives in good yields under mild and environmentally benign conditions. Among the different Lewis acids tested, gold(III) proved to be the catalyst of choice for both chemical (yield, conversion) and practical reasons (a filtration over a silica pad is generally sufficient to obtain the
friendly method for the direct amination of secondary benzyl alcohols with amides or 4-nitroaniline is described. This method has been applied to a variety of substrates, and the reaction proceeded smoothly at room temperature under solvent-free conditions. CbzNH2 was proved to be very useful in the direct preparation of the benzylic amines from corresponding alcohols.
tolerates aerobic conditions. A Hammett study in the reaction of para-substituted benzhydryl alcohols shows negative σ values, indicating a build-up of cationic charge during the rate-determining sp3 C–O bond-cleavage step. The inverse kinetic solvent isotope effect (KSIE = 0.6) is consistent with a specific acid catalysis mechanism. This simple protocol can be performed under mild conditions in an atom-economic