Enantioselective Reduction of Electrophilic C?C Bonds with sodium tetrahydroborate and ?semicorrin? cobalt catalysts
作者:Marian Misun、Andreas Pfaltz
DOI:10.1002/hlca.19960790404
日期:1996.6.26
‘Semicorrin’ cobalt complexes, prepared in situ from cobalt(II) chloride and the corresponding ligands, are efficient catalysts for the enantioselective reduction of electrophilic CC bonds with NaBH4. The best selectivities (> 90% ee) are achieved with α,β-unsaturated carboxamides and carboxylates. Analogous α,β-unsaturated nitriles, sulfones, and phosphonates afford enantiomeric excesses of 50–70%
由氯化钴(II)和相应的配体原位制备的“ Semicorrin”钴络合物是有效的催化剂,用于与NaBH 4对映选择性还原亲电CC键。用α,β-不饱和羧酰胺和羧酸盐可获得最佳选择性(> 90%ee)。类似的α,β-不饱和腈,砜和膦酸酯的对映体过量为50-70%。有趣的是,在α,β-不饱和砜的还原中,不对称的“半corrins”获得了最高的对映选择性,而在所有其他情况下,C 2对称的“半corrins”被证明是更好的。