through a cascadereaction between 2‐isocyanoethylindole and alkylidene malonates catalyzed by a chiral N,N′‐dioxide/MgII catalyst. Fused polycyclic indolines containing three stereocenters were afforded in good yields with excellent diastereo‐ and enantioselectivities through a Michael/Friedel–Crafts/Mannich cascade. When 2‐substituted 2‐isocyanoethylindoles were used, spiroindoline derivatives were obtained
Catalytic asymmetric synthesis of hydrothiazole derivatives was developed via a well-organized formal [2 + 1 + 2] cycloaddition reaction triggered by asymmetric addition of isocyanide to alkylidene malonate. Various chiral hydrothiazole derivatives were readily provided in good yield with high enantioselectivity (up to 98% yield, 98.5:1.5 er) utilizing a chiral Mg(OTf)2/N,N'-dioxide complex as the
Synthesis of 3-Oxazolines via SnCl4-Promoted Formal [3+2] Cycloaddition of Donor–Acceptor Oxiranes and Nitriles
作者:Xiaofei Zeng、Guofu Zhong、Hai Zhou、Yan Xie
DOI:10.1055/s-0034-1380216
日期:——
A novel SnCl4-promoted formal [3+2] cycloaddition of donor–acceptor oxiranes and nitrilesvia chemoselective C–C bond breakage was developed. This reaction provides an efficient and practical method for the preparation of 3-oxazolines in good yields (up to 89%).
CO Versus CC Bond Cleavage: Selectivity Control in Lewis Acid Catalyzed Chemodivergent Cycloadditions of Aryl Oxiranyldicarboxylates with Aldehydes, and Theoretical Rationalizations of Reaction Pathways
A clean break: Lewisacidcatalyzedchemodivergent [3+2] cycloadditions of aryloxiranyldicarboxylates with aldehydes are revealed, in which the CC or CObondcleavage of oxiranes can be controlled by the use of Ni(ClO4)2 or Sn(OTf)2 catalysts (see scheme). Possible reactionpathways for these transformations are demonstrated by theoretical calculations.
Scandium(III) Trifluoromethanesulfonate Catalyzed Selective Reactions of Donor-Acceptor Cyclopropanes with 1,1-Diphenylethanols: An Approach to Polysubstituted Olefins
作者:Xiaoyan Zhu、Gang Hong、Chen Hu、Shengying Wu、Limin Wang
DOI:10.1002/ejoc.201700221
日期:2017.3.17
An unexpected synthetic approach to polysubstituted olefins through the scandium(III) trifluoromethanesulfonate catalyzed ring-opening reaction of donor–acceptor cyclopropanes with 1,1-diphenylethanols was developed. The reactions, which are experimentally easy to handle, feature tolerance of various functional groups and mild reaction conditions. On the basis of experimental evidence, a plausible