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Enantioselective Reduction of Electrophilic CC Bonds with sodium tetrahydroborate and ‘semicorrin’ cobalt catalysts
Author(s) -
Misun Marian,
Pfaltz Andreas
Publication year - 1996
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19960790404
Subject(s) - chemistry , enantioselective synthesis , cobalt , electrophile , catalysis , enantiomer , medicinal chemistry , sodium , organic chemistry
‘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 NaBH 4 . 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%. Interestingly, in the reduction of α,β‐unsaturated sulfones, the highest enantioselectivities were obtained with unsymmetrical ‘semicorrins’, whereas in all other cases C 2 ‐symmetric ‘semicorrins’ proved to be superior.