Chiral intramolecular amine-borane complexes as reducing agents for prochiral ketones
作者:Jean-Brice Le Toumelin、Michel Baboulène
DOI:10.1016/s0957-4166(97)00093-1
日期:1997.4
A new family of chiral amine-borane complexes the N-spiroazaborolidines 4 is synthesized. These compounds are stable, convenient to use and have proved to be excellent reducingagents of prochiralketones (yieldreduction≥95%). However, a poor enantioselectivity was obtained (ee<-38%). The configuration of these molecules (cis position between Baza and the substituent on the Boxaza), unfavourable for
Chirality Transfer in Azetidinium
Ylides: An Enantioselective Route to α-Quaternary
Azetidines
作者:François Couty、Bruno Drouillat、Jérome Marrot
DOI:10.1055/s-0028-1087939
日期:——
Enantiomerically pure N-allyl azetidinium ions undergo a stereoselective [2,3]-sigmatropic shift to give azetidines with an α-quaternary center. These compounds are direct precursors of 2-alkyl-2-carboxy-azetidines, a new class of constrained α-amino acids.