Asymmetric Synthesis of Dihydropyranones via Gold(I)‐Catalyzed Intermolecular [4+2] Annulation of Propiolates and Alkenes
作者:Hanbyul Kim、Su Yeon Choi、Seunghoon Shin
DOI:10.1002/anie.201807514
日期:2018.10
Intermolecular asymmetric gold catalysis involving alkyne activation presents a significant challenge due to its distinct mechanistic mode from other metals. Herein, we report a highly enantioselective synthesis of α,β‐unsaturated δ‐lactones from [4+2] annulation of propiolates and alkenes in upto 95 % ee. Notably, for the desired chiral recognition, the choice of 1,1,2,2‐tetrachloroethane as solvent
The chiraltitanium complex-catalyzed ene-type reaction and the Mukaiyama aldolreaction with fluoral are shown to serve as an efficient route to the enantioselective and diastercoselective synthesis of CF3-substituted components of biological and synthetic importance.
Diastereo- and enantioselective carbony-ene reaction of glyoxylate (2) with trisubstituted olefins (3) catalyzed by chiral titanium complexes (1a), derived from 6,6'-dibromo-1,1'-bi-2-naphthol and disopropoxytitanium dihalides, is found to provide syn-diastereomers exclusively along with a high level of enantioselectivity.
<b>Proximity Effects. XXXIII. Solvolysis of <b><i>trans</i></b>-Bicyclo[6.1.0]nonane</b>