STUDIES ON CHIRAL THIOPHOSPHORIC ACIDS AND THEIR DERIV ATIVES 16.-THE ASYMMETRIC CYCLIZATION OF L-(+)- PROLINOL WITH (THIO)PHOSPHORO(-NO)DICHLORIDATES
摘要:
The cyclizations of L-(+)-prolinol 5 with (thio)phosphoro(-no)dichloridates 6 give 1,2,3-azaphosphaoxabicyclo[3.3.0]octanes 7 consisting of unequal amounts of diastereoisomers, eight pairs of which have been successfully resolved by silica gel column chromatography or recrystallization. The influences of reaction temperature, solvent and substrate concentration upon the asymmetric induction have also been investigated.
Chiral phosphinamides: new catalysts for the asymmetric reduction of ketones by borane
作者:Barry Burns、N. Paul King、Heather Tye、John R. Studley、Mark Gamble、Martin Wills
DOI:10.1039/a709174e
日期:——
We have identified a new class of catalysts for the asymmetricreduction of prochiral ketones by borane. Key to the architecture of effective catalysts is an N–PO structural unit which may be part of a phosphinamide, phosphonamide or a related structure. Such catalysts are simple to prepare, are often crystalline solids and may be recovered from reduction reactions and reused. The catalysts act essentially