title: Asymmetric intermolecular C-H functionalization of benzyl silyl ethers mediated by chiral auxiliary-based aryldiazoacetates and chiral dirhodium catalysts.
abstract: [reaction: see text] C-H functionalization of benzyl silyl ethers by means of rhodium-catalyzed insertions of aryldiazoacetates can be achieved in a highly diastereoselective and enantioselective manner by judicious choice of chiral catalyst or auxiliary. The dirhodium tetraprolinates such as Rh2((S)-DOSP)4 have been widely successful as chiral catalysts in the C-H functionalization chemistry of aryldiazoacetates, but give poor enantioselectivity in the reactions of aryldiazoacetates with benzyl silyl ether derivatives. The use of (S)-lactate as a chiral auxiliary resulted in C-H functionalization with moderately high diastereoselectivity (79-88% de) and enantioselectivity (68-85% ee). The best results (91-95% de, 95-98% ee), however, were achieved using Hashimoto's Rh2((S)-PTTL)4 catalyst.
authors.affiliation: Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260-3000, USA. hdavies@acsu.buffalo.edu
authors.forename: Huw M L
authors.initials: HM
authors.lastname: Davies
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Hedley
authors.forename: Brooks R
authors.initials: BR
authors.lastname: Bohall