Desymmetrization of prochiral phosphanes using derivatives of (-)-cytisine
Artikel i vetenskaplig tidskrift, 2004
yHistorically, (-)-sparteine-sec-BuLi has been used to desym-metrize prochiral phosphanes. In this report, derivatives of an alkaloid extracted from the seeds of Laburnum anagyro-ides have been utilized to mimic (+)-sparteine, which is not readily available. In several cases, the enantioselectivities achieved with the (+)-Sparteine surrogates outperformed (-)-sparteine itself in the deprotonation of alkyl-substituted (as well as aryl-substituted) prochiral phosphane derivatives. In addition, use of these surrogates allows a new methodology for a chiral switch in phosphorus chemistry. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).
CATALYZED ASYMMETRIC HYDROGENATION