ASYMMETRIC CARBONYL ADDITION-REACTIONS TO BENZYLOXYALDEHYDES BY BINAPHTHOL-TITANIUM CATALYST ANTI-DIASTEREOFACIAL VS SYN-DIASTEREOFACIAL PREFERENCE IN ANOMALOUS NONCHELATION COMPLEXATION
K. Mikami et al., ASYMMETRIC CARBONYL ADDITION-REACTIONS TO BENZYLOXYALDEHYDES BY BINAPHTHOL-TITANIUM CATALYST ANTI-DIASTEREOFACIAL VS SYN-DIASTEREOFACIAL PREFERENCE IN ANOMALOUS NONCHELATION COMPLEXATION, Tetrahedron letters, 38(11), 1997, pp. 1951-1954
An anomalous nonchelation diastereofacial selectivity is observed in t
he titanium-catalyzed carbonyl addition reaction to benzyl-protected a
lkoxyaldehydes. There is a dichotomy in the sense of syn- vs. anti-dia
stereofacial preference, dictated by the bulkiness of the migratory gr
oup: The sterically demanding silyl group gives syn-diastereofacial pr
eference and the less sterically demanding proton lends to anti-diaste
reofacial preference. (C) 1997 Elsevier Science Ltd.