Chiral Cyclometalated Oxazoline Gold(III) Complex-Catalyzed Asymmetric Carboalkoxylation of Alkynes
作者:Jia-Jun Jiang、Jian-Fang Cui、Bin Yang、Yulu Ning、Nathanael Chun-Him Lai、Man-Kin Wong
DOI:10.1021/acs.orglett.9b02171
日期:2019.8.16
O′-chelated 4,4′-biphenol cyclometalated oxazoline gold(III) complexes has been developed. A high yield (≤89%) and a high enantioselectivity (≤90% ee) were achieved in asymmetric carboalkoxylation of alkynes. Enantioselectivity could be significantly improved from 19% to 90% ee by increasing the steric size of the substituent on the chiral oxazoline ligand. Catalytically active AuIII species and the origin
A General, Asymmetric, and Noniterative Synthesis of Trideoxypropionates. Straightforward Syntheses of the Pheromones (+)-Vittatalactone and (+)-Norvittatalactone
作者:Christian F. Weise、Matthias C. Pischl、Andreas Pfaltz、Christoph Schneider
DOI:10.1021/jo202330b
日期:2012.2.3
A novel, highly stereocontrolled, and very flexible synthetic access to biologically relevant trideoxypropionate building blocks in optically pure form has been developed. On the basis of a three-step sequence comprising a thermal oxy-Cope rearrangement, an iridium-catalyzed hydrogenation, and an auxiliary-controlled enolate methylation, trideoxypropionates with easily adjustable relative configuration were synthesized in excellent yields. In addition, the functionalized end groups allow for chemoselective manipulations and further elongation of the chain. The underlying strategy constitutes the first noniterative process for the assembly of polydeoxypropionates and has further been applied in total syntheses of the pheromones (+)-vittatalactone and (+)-norvittatalactone, which had been isolated from the striped cucumber beetle Acalymma vittatum.