Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
Chemistry. 2018 Jul 5;24(38):9520-9524. doi: 10.1002/chem.201802273. Epub 2018 May 30.
The first direct enantioselective α-allylation of unfunctionalized cyclic ketones using alkynes as an economical choice of reagent is reported. This transformation uses a simple procedure with commercially available palladium, chiral bisphosphine ligand and chiral amine catalysts, and affords valuable ketones with a α-tertiary stereocenter in good to high enantiopurity. In this transformation, a chiral palladium complex containing the (S)-DIFLUORPHOS ligand catalyzes the isomerization of alkynes into an electrophilic allylpalladium species, which is attacked by the enamine generated in situ from the condensation of (R)-prolinol with the ketone substrate.
本文报道了首例未功能化环状酮的首例直接对映选择性α-烯丙基化反应，该反应使用炔烃作为经济选择的试剂。这种转化使用了一种简单的程序，使用商业可得的钯、手性双膦配体和手性胺催化剂，以良好至高对映选择性提供具有α-叔立体中心的有价值的酮。在这种转化中，含有（S）-DIFLUORPHOS 配体的手性钯配合物催化炔烃异构化为亲电烯丙基钯物种，该物种被（R）-脯氨酸与酮底物缩合原位生成的烯胺进攻。
