Enantioselective conjugate reduction of α,β-unsaturated carboxamides with semicorrin cobalt catalysts
摘要:
Chiral semicorrin cobalt complexes, prepared in situ from cobalt(II) chloride and the free ligands, are efficient, highly enantioselective catalysts for the conjugate reduction of alpha,beta-unsaturated carboxamides with sodium borohydride. Enantiomeric excesses of up to 99 %, essentially quantitative yields, and high substrate/catalyst ratios (1 000 - 10 000:1) are attractive attributes of this catalytic process.
Azabis(oxazolines) prove to be superior ligands for the enantioselective, cobalt(II)-catalyzed conjugatereduction of α,β-unsaturated carbonylcompounds with sodium borohydride. β-Trisubstituted α,β-unsaturated esters and amides as well as γ-butenolides are readily converted to their corresponding saturated counterparts with enantioselectivities up to 97% ee.
Pfaltz, Andreas, Bulletin des Societes Chimiques Belges, 1990, vol. 99, # 9, p. 729 - 739
作者:Pfaltz, Andreas
DOI:——
日期:——
Metalated unsaturated amides. Regio- and stereoselective .gamma.-alkylation
作者:M. Majewski、G. B. Mpango、M. T. Thomas、A. Wu、V. Snieckus
DOI:10.1021/jo00323a012
日期:1981.5
OAKLEAF J. A.; THOMAS M. T.; WU A.; SNIECKUS V., TETRAHEDRON LETT., 1978, NO 19, 1645-1648
作者:OAKLEAF J. A.、 THOMAS M. T.、 WU A.、 SNIECKUS V.
DOI:——
日期:——
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’ cobaltcomplexes, 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%