An efficient method for the preparation of C2-symmetric, chiral alk-2-ene-1,4-diols (4) has been achieved, based on the borane-mediated reduction of symmetric alk-2-ene-1,4-diones (2) in the presence of oxazaborolidine (R)-1. In general, the presence of the double bond in 2 has been beneficial (compared with the related saturated 1,4-diketones 3) not only as far as the stereoselectivity in the reduction
4-diarylbutane-1,4-diols and their derivatives, increasingly considerable attention has been paid to developing effective synthetic methods for chiral 1,4-diarylbutane-1,4-diols. We herein report an efficient asymmetric hydrogenation of 1,4-diaryldiketones catalyzed by a chiral iridium complex bearing f-amphox as ligand, furnishing a series of 1,4-diarylbutane-1,4-diols in excellent yields (up to >99%) with exceptional
Asymmetricreduction of 1,4-diphenylbutane-1,4-dione (1) was carried out using the reducing agents NaBH 4 , BH 3 .THF, and PhNEt 2 .BH 3 in combination with the chiral reagents (S)-(-)-α,α-diphenyl-2-pyrrolidinemethanol (4) or (S)-proline (5), in the presence of TMSCI or B(OMe) 3 under various conditions to obtain the corresponding 1,4-diol 2 in 52% to 97% ee. The chiral 1,4-diol 2 was converted to
Asymmetric hydrogenation of diaryl 1,4-diketones was achieved by using trans-RuCl2[(S)-BINAP)][(S)-Daipen] as the catalyst and the reaction gave rise to excellent enantio- and diastereoselectivities (up to >99% ee and de). This procedure provides a convenient and efficient synthetic method for chiral 1,4-diarylbutane-1,4-diols, which are important intermediates for a variety of chiralauxiliaries and
使用反式-RuCl 2 [( S )-BINAP)][( S )-Daipen] 作为催化剂实现了二芳基 1,4-二酮的不对称氢化,反应产生了优异的对映选择性和非对映选择性(高达 > 99% ee和de )。该方法为手性 1,4-二芳基丁烷-1,4-二醇提供了一种方便有效的合成方法,该方法是多种手性助剂和配体的重要中间体。
A Novel Phosphinamide Catalyst for the Asymmetric Reduction of Ketones by Borane