for α,β-disubstituted α,β-unsaturated esters is performed via three general and robust reaction sequences: (i) Ti−Claisen condensation (formylation) of esters to give α-formyl esters (12 examples, 60−99%), (ii) (E)- and (Z)-stereocomplementary enol p-toluenesulfonylation (tosylation) using TsCl−N-methylimidazole (NMI)−Et3N and LiOH (24 examples, 82−99%), and (iii) stereoretentive Suzuki−Miyaura cross-coupling
P(NMe<sub>2</sub>)<sub>3</sub>-Mediated Umpolung Alkylation and Nonylidic Olefination of α-Keto Esters
作者:Sunewang Rixin Wang、Alexander T. Radosevich
DOI:10.1021/acs.orglett.5b01784
日期:2015.8.7
A commercial phosphorus-based reagent (P(NMe2)(3)) mediates,umpolung alkylation of methyl aroylformates with benzylic and allylic bromides, leading to either Barer-type addition or ylide-free olefination products upon workup. The reaction sequence is initiated, by a two-electron redox addition of the tricoordinate phosphorus reagent with an alpha-keto ester Compound (Kukhtin-Ramirez addition). A mechanistic rationale is offered for the chemoselectivity upon which the success of this nonmetal mediated C-C bond forming strategy is based.
Ru-Catalyzed C–H Arylation of Acrylic Acids with Aryl Bromides
作者:Florian Belitz、Ann-Katrin Seitz、Jonas F. Goebel、Zhiyong Hu、Lukas J. Gooßen