The highly enantioselective Diels–Alderreaction of acetylenic dienophiles is shown to be effectively catalyzed by cationic chiral palladium complexes. Not only the degree but also the sense of enantioselectivity critically depends on the steric demand of ligands. Computational analyses indicate that the steric demand does not affect the endo/exo‐selectivity but the enantioface selectivity of dienes
Enantioselective Friedel−Crafts Reaction of Indoles with Carbonyl Compounds Catalyzed by Bifunctional Cinchona Alkaloids
作者:Hongming Li、Yong-Qiang Wang、Li Deng
DOI:10.1021/ol061552a
日期:2006.8.1
asymmetric Friedel-Craftsreaction that, unprecedently, is applicable to a wide range of both indoles and carbonyls. The use of a readily accessible catalyst in combination with a high enantioselectivity that is insensitive to reaction concentration, temperature, air, and moisture should allow this reaction to provide useful enantioselective access to new chiral indole derivatives. [reaction: see text]
affording various tetrasubstituted thiophenes with aryl, alkenyl, alkyl, or silylgroup at the special position. The structural modification of alkyne substrates enabled the synthesis of diverse thiophenes to be achieved using the pyridinium 1,4-zwitterionic thiolates as the sulfur-containing building blocks. This approach is metal-free and catalyst-free.
from alkynyl ketoesters was developed. Excellent yields and enantioselectivities were obtained from the reaction using bis(imidazoline)-Zn(II) catalyst. Based on experiments and MO calculation, a plausible transition state was proposed to explain the stereoselectivity of the reaction. The obtained products were converted into various amines and a lactam. This process provides an efficient route for
开发了无环乙烯基烯酮甲硅烷基缩醛与衍生自炔基酮酯的无环酮亚胺的第一个对映选择性乙烯基曼尼希反应。从使用双(咪唑啉)-Zn(II)催化剂的反应中获得了优异的产率和对映选择性。基于实验和 MO 计算,提出了一个合理的过渡态来解释反应的立体选择性。所得产物被转化为各种胺和内酰胺。该方法为合成无环δ-氨基-α,β-不饱和羰基化合物及其衍生物提供了有效途径。
Synthesis of 17-Deacetoxyl Chromodorolide B Based on a Gold-Catalyzed Alkoxycyclization Reaction
作者:Chen Li、Tianfei Quan、Yibin Xue、Yuhui Cao、Si-Cong Chen、Tuoping Luo
DOI:10.1021/acs.orglett.0c00247
日期:2020.2.21
A novel strategy to construct the highly oxidized 3-oxabicyclo[3.3.0]octane skeleton was developed via a gold-catalyzed cascade cyclization with 2,7-dioxabicyclo[3.2.0]hept-3-ene as the substrate. We utilized this methodology as the key reaction to synthesize 17-deacetoxyl chromodorolide B.