Affiliation:
1. Department of Chemistry Renmin University of China 100872 Beijing China
2. State Key Laboratory of Chemical Resource Engineering Institute of Computational Chemistry College of Chemistry Beijing University of Chemical Technology 100029 Beijing China
3. Roy and Diana Vagelos Laboratories Penn/Merck Laboratory for High-Throughput Experimentation Department of Chemistry University of Pennsylvania 231 South 34th Street PA 19104-6323 Philadelphia USA
4. Beijing National Laboratory for Molecular Sciences and Institute of Chemistry Chinese Academy of Sciences 100190 Beijing China
Abstract
AbstractRecent years have witnessed marked progress in the efficient synthesis of various enantioenriched 1,2,3,4‐tetrahydroquinoxalines. However, enantio‐ and diastereoselective access to trans‐2,3‐disubstituted 1,2,3,4‐tetrahydroquinoxalines remains much less explored. Herein we report that a frustrated Lewis pair‐based catalyst generated via in situ hydroboration of 2‐vinylnaphthalene with HB(C6F5)2 allows for the one‐pot tandem cyclization/hydrosilylation of 1,2‐diaminobenzenes and 1,2‐diketones with commercially available PhSiH3 to exclusively afford trans‐2,3‐disubstituted 1,2,3,4‐tetrahydroquinoxalines in high yields with excellent diastereoselectivities (>20 : 1 dr). Furthermore, this reaction can be rendered asymmetric by using an enantioenriched borane‐based catalyst derived from HB(C6F5)2 and a binaphthyl‐based chiral diene to give rise to enantioenriched trans‐2,3‐disubstituted 1,2,3,4‐tetrahydroquinoxalines in high yields with almost complete diastereo‐ and enantiocontrol (>20 : 1 dr, up to >99 % ee). A wide substrate scope, good tolerance of diverse functionality and up to 20‐gram scale production are demonstrated. The enantio‐ and diastereocontrol are achieved by the judicious choice of borane catalyst and hydrosilane. The catalytic pathway and the origin of the excellent stereoselectivity are elucidated by mechanistic experiments and DFT calculations.
Funder
Division of Chemistry
National Natural Science Foundation of China
Beijing National Laboratory for Molecular Sciences