Boronenolates bearing menthone-derived chiral ligands are capable of fair to excellent diastereocontrol in their reactions with chiral aldehydes. Thioester-derived (better than ketone derived) enolates are able to control aldol stereochemistry irrespective of the aldehyde preferences. With thioacetate-derived chiralenolates and enantiopure N,N-dibenzyl α-amino aldehydes, either the 3,4-anti or the
Boron enolates bearing menthone-derived chiral ligands are capable of fair to excellent diastereocontrol in their reactions with chiral aldehydes. Thioester-derived (better than ketone derived) enolates are able to control aldol stereochemistry irrespective of the aldehyde preferences.
Asymmetric carbonyl addition reactions to benzyloxyaldehydes by binaphthol-titanium catalyst: Anti- vs. Syn-diastereofacial preference in anomalous nonchelation complexation
作者:Koichi Mikami、Satoru Matsukawa、Eiji Sawa、Akinori Harada、Nobuaki Koga
DOI:10.1016/s0040-4039(97)00231-1
日期:1997.3
An anomalous nonchelation diastereofacial selectivity is observed in the titanium-catalyzed carbonyl addition reaction to benzyl-protected alkoxyaldehydes. There is a dichotomy in the sense of syn- vs. anti-diastereofacial preference, dictated by the bulkiness of the migratory group: The sterically demanding silyl group gives syn-diastereofacial preference and the less sterically demanding proton lends to anti-diastereofacial preference. (C) 1997 Elsevier Science Ltd.
GENNARI, CESARE;COZZI, PIER GIORGIO, TETRAHEDRON, 44,(1988) N 18, C. 5965-5974