Nickel complexes from α-amino amides as efficient catalysts for the enantioselective Et2Zn addition to benzaldehyde
摘要:
Ni2+ complexes derived from simple alpha-amino amides catalyze very efficiently the addition of Et2Zn to benzaldehyde, giving (S)-1-phenylethanol as the major isomer in most cases (94% yield, 97% ee for R=Bn). The nature of the substituent on the amide nitrogen atom seems to play a key role in determining the asymmetric induction observed. (C) 2003 Elsevier Ltd. All rights reserved.
Enantioselectivealdolreactions of various isatins with ketones using newly designed amino amide organocatalysts were found to provide chiral 3-substituted 3-hydroxy-2-oxindoles in good to excellent yields and with excellent stereoselectivities (up to 99 %, up to 98 % ee, syn/anti = 99:1); one catalyst, 3i, proved particularly successful. One of the resulting oxindoles, 3-hydroxy-3-(2-oxocyclohexyl)-2-indolinone
Enantioselective nickel-catalyzed conjugate addition of dialkylzinc to chalcones using chiral α-amino amides
作者:Jorge Escorihuela、M. Isabel Burguete、Santiago V. Luis
DOI:10.1016/j.tetlet.2008.09.120
日期:2008.11
A series of alpha-amino amides derived from natural amino acids (alanine, valine, phenylalanine, isoleucine, and phenylglycine) have been synthesized and fully characterized. Their Ni(II) complexes prepared from Ni(acac)(2) catalyze the enantioselective conjugate addition of diethylzinc to chalcones in high yields and in good enantioselectivities (up to 84%). The side chain of the amino acid and the substituents in the amide nitrogen govern the enantioselectivity of the catalytic process. (c) 2008 Elsevier Ltd. All rights reserved.