The asymmetric alkynylation of aliphatic and aromatic aldehydes with propiolates was mediated by dialkylzinc and a novel prolinol catalyst without high reagent loading and any additives, such as Ti(Oi-Pr)4, to give the corresponding γ-hydroxy-α,β-acetylenic esters with high enantiomeric excess of up to 95%.
3,3′-Anisyl-Substituted BINOL, H<sub>4</sub>BINOL, and H<sub>8</sub>BINOL Ligands: Asymmetric Synthesis of Diverse Propargylic Alcohols and Their Ring-Closing Metathesis to Chiral Cycloalkenes
作者:Yang Yue、Mark Turlington、Xiao-Qi Yu、Lin Pu
DOI:10.1021/jo9018446
日期:2009.11.20
aldehydes. It catalyzed the reactions of alkyl propiolates with 88−99% ee; the reactions of phenylacetylene with 81−87% ee; the reactions of 4-phenyl-1-butyne, an alkyl alkyne, with 77−89% ee; and the reactions of trimethylsilylacetylene with 92−97% ee. The optically active propargylic alcohols generated from this catalytic asymmetric alkyne addition were observed to undergo efficient ring-closing-metathesis