Three chiral pyridinylmethyl pyrrolidinemethanol derivatives have been synthesized from N-alkylation of (S)-alpha,alpha-diphenyl-2-pyrrolidinemethanol and N-carbonylation Of L-proline methyl ester. The catalytic asymmetric borane reduction of prochiral ketones was examined in the presence of chiral oxazaborolidine catalysts prepared in situ from chiral pyridinylmethyl pyrrolidinemethanol derivatives. The corresponding chiral secondary alcohols were obtained with good to excellent enantiomeric excesses (up to 98% ee) using (S)-2-(diphenylmethanol)-1-(2-pyridylmethyl)pyrrolidine I in THF at reflux and moderate to good enantiomeric excesses using C-2-symmetric compound 2 (up to 86% ee) in THE. (C) 2003 Elsevier Ltd. All rights reserved.
Asymmetric catalysis, part 91: Enantioselective monophenylation ofcis-1,2-cyclopentanediol with triphenylbismuth diacetate and chiral copper(II) complexes as catalysts
作者:H. Brunner、T. Chuard
DOI:10.1007/bf00811078
日期:1994.12
The monophenylation of cis-1,2-cyclopentanediol with triphenylbismuth diacetate in the presence of chiral Cu(II) complexes as catalysts gave cis-2-hydroxy-1-phenoxy-cyclopentane with enantiomeric excesses up to 38%. The optically active ligands used were triamine derivatives of 2,6-bis(aminomethyl)pyridine and diamine derivatives of 2-(aminomethyl)pyridine. Selectivity in the monophenylation occurred only in the presence of the latter as auxiliary ligands.
Chiral ligands containing heteroatoms. 6. 1-(2-Pyridylmethyl)pyrrolidine in the chiral catalysis of addition of diethylzinc to benzaldehyde.