Enantioselective 1,6-Conjugate Addition of Dialkylzinc Reagents to Acyclic Dienones Catalyzed by Cu-DiPPAM Complex-Extension to Asymmetric Sequential 1,6/1,4-Conjugate Addition.
Résumé
Sodium L-N-[[2-(diphenylphosphino)phenyl]methylene]-3-methylvaline (DiPPAM) and (R)-BINAP ligands led to divergent behaviors in the copper-catalyzed regio- and enantioselective conjugate addn. of dialkylzinc reagents R12Zn (R1 = Me, Et, i-Pr, n-Bu) to linear α,β-unsatd. ketones and dienones R2CH:CHCOR3 (R2 = Me, i-Bu, n-pentyl, Ph, MeCH:CH, PhCH:CH, n-C7H15CH:CH, etc.; R3 = Me, Ph, 4-MeOC6H4, etc.), which were applied to the development of a highly selective sequential asym. 1,6/1,4-conjugate addn. process. [on SciFinder(R)]