Enantioselective Synthesis of Homoallylic Amines through Reactions of (Pinacolato)allylborons with Aryl-, Heteroaryl-, Alkyl-, or Alkene-Substituted Aldimines Catalyzed by Chiral <i>C</i><sub>1</sub>-Symmetric NHC−Cu Complexes
作者:Erika M. Vieira、Marc L. Snapper、Amir H. Hoveyda
DOI:10.1021/ja200311n
日期:2011.3.16
A catalytic method for enantioselective synthesis of homoallylamides through Cu-catalyzed reactions of stable and easily accessible (pinacolato)allylborons with aryl-, heteroaryl-, alkyl-, or alkenyl-substituted N-phosphinoylimines is disclosed. Transformations are promoted by 1-5 mol % of readily accessible NHC-Cu complexes, derived from C(1)-symmetric imidazolinium salts, which can be prepared in
A Direct Catalytic Asymmetric Mannich-type Reaction via a Dinuclear Zinc Catalyst: Synthesis of Either <i>anti</i>- or <i>s</i><i>yn</i>-α-Hydroxy-<i>β</i>-Amino Ketones
作者:Barry M. Trost、Jaray Jaratjaroonphong、Vichai Reutrakul
DOI:10.1021/ja057498v
日期:2006.3.1
The use of imines bearing a hydrolyzable nitrogen substituent in direct asymmetric Mannich reactions with α-hydroxyketones is developed. Previous work focused on the use of N-arylimines or nonenolizable imines, and the latter with only methoxy-substituted α-hydroxyacetophenones. Using a dinuclearcatalyst devised from 2,6-di-(S)-2‘-diphenylhydroxymethylpyrrolidino-N-methyl)-4-methylphenol and diethylzinc
Direct catalytic asymmetric Mannich-type reactions of isomerizable aliphatic imines: chemoselective enolate formation from a hydroxyketone by a Zn-catalyst
A direct catalyticasymmetric Mannich-type reaction of isomerizable aliphaticimines is described. A Et2Zn/(S,S)-linked-BINOL complex was suitable for chemoselective enolate formation from a hydroxyketone in the presence of isomerizable aliphatic N-diphenylphosphinoyl imines. The reaction proceeds smoothly and β-alkyl-β-amino-α-hydroxyketones were obtained in good yield and high enantioselectivity
NHC–Cu-Catalyzed Addition of Propargylboron Reagents to Phosphinoylimines. Enantioselective Synthesis of Trimethylsilyl-Substituted Homoallenylamides and Application to the Synthesis of <i>S</i>-(−)-Cyclooroidin
作者:Nicholas W. Mszar、Fredrik Haeffner、Amir H. Hoveyda
DOI:10.1021/ja500373s
日期:2014.3.5
A catalytic method for the efficient and enantioselective addition of a 1-trimethylsilyl-substituted allene moiety to phosphinoylimines is presented. Transformations are promoted by 5.0 mol % of a copper complex of an N-heterocyclic carbene in the presence of a propargylboron reagent that can be readily prepared in multigram quantities. Within 10 min of reaction, products are obtained in up to 91% yield, 98% allene (vs propargyl) selectivity, and 98:2 enantiomeric ratio. An assortment of aldimines serve as suitable substrates. The phosphinoyl and silyl groups can be removed efficiently and orthogonally. The silylallene moiety may be transformed to versatile derivatives that are difficult to access via nonsilylated allenes. The special features and utility of the approach are highlighted through a succinct enantioselective synthesis of marine alkaloid S-(-)-cyclooroidin.