Pd(II)/Brønsted Acid Catalyzed Enantioselective Allylic C–H Activation for the Synthesis of Spirocyclic Rings
作者:Zhuo Chai、Trevor J. Rainey
DOI:10.1021/ja2102407
日期:2012.2.29
A Pd(II)/Brønsted acid catalyzed migratory ring expansion for the synthesis of indene derivatives possessing a stereogenic spirocyclic carbon center was developed. This transformation is believed to mechanistically proceed via enantioselective allylic C-H activation with concomitant semipinacol ring expansion to the nascent π-allylpalladium species. Enantioselectivities as high as 98% ee were attainable
开发了 Pd(II)/Brønsted 酸催化的迁移环扩张,用于合成具有立体螺环碳中心的茚衍生物。这种转变被认为是通过对映选择性烯丙基 CH 活化以及伴随的半频哪醇环扩展到新生的 π-烯丙基钯物质而在机械上进行的。可获得高达 98% ee 的对映选择性。
Asymmetric Baeyer-VilligerOxidation of Prochiral Cyclobutanones Using a Chiral CationicPalladium(II) 2-(Phosphinophenyl)pyridine Complex as Catalyst
palladium(II) 2-(phosphinophenyl)pyridine (1a) complex was found to be an effective catalyst for asymmetricBaeyer-Villigeroxidation of prochiral cyclobutanones. For example, good and excellent enantioselectivities (80% and >99% ees) were achieved in the reactions of 3-phenylcyclobutanone and a tricyclic cyclobutanone, respectively.
A TiCl4-promoted cascade formal [3 + 2] cycloaddition/double ring-opening/chlorination of 2-furylcyclobutanols with alkyl or aryl azides is described. This highlyefficient transformation involves the formation/cleavage of several C–N, C–Cl, C–C, and C–O bonds in a single operation. It enables the quick construction of trisubstituted 1,2,3-triazoles with an (E)-enone moiety and a 3-chloropropyl unit
An ion-pair catalyst generated by assembly of a chiral flavinium and a cinchona alkaloid dimer for use in asymmetricBaeyer-Villigeroxidation is presented.