The first highly enantioselective hydrogenation of simple indoles was developed with a Brønstedacid as an activator to form the iminium intermediate in situ, which was hydrogenated using Pd(OCOCF(3))(2)/(R)-H8-BINAP catalyst system with up to 96% ee. The present method provides an efficient route to enantioenriched 2-substituted and 2,3-disubstituted indolines.
98% ee using a strong Brønsted acid as the activator. This methodology was applied in the facile synthesis of biologically active products containing a chiral indoline skeleton. The mechanism of Pd-catalyzed asymmetric hydrogenation was investigated as well. Isotope-labeling reactions and ESI-HRMS proved that an iminium salt formed by protonation of the C═C bond of indoles was the significant intermediate
Asymmetric hydrogenation of unprotected indoles using iridium complexes derived from P–OP ligands and (reusable) Brønsted acids
作者:José Luis Núñez-Rico、Héctor Fernández-Pérez、Anton Vidal-Ferran
DOI:10.1039/c3gc42132e
日期:——
stepwise process: (reusable) Brønsted acid-mediated CC isomerisation and asymmetrichydrogenationusing enantioselective iridium catalysts derived from P–OP ligands. This straightforward combination of (reusable) Brønstedacids, which activate the indole ring for hydrogenation by breaking its aromaticity, and enantiomerically pure [Ir(P–OP)]+ complexes as hydrogenation catalysts affords the resulting
Asymmetric Transfer Hydrogenation of N-Unprotected Indoles with Ammonia Borane
作者:Weiwei Zhao、Zijia Zhang、Xiangqing Feng、Jing Yang、Haifeng Du
DOI:10.1021/acs.orglett.0c01930
日期:2020.8.7
A metal-free asymmetric transfer hydrogenation of unprotected indoles was successfully realized using a catalyst derived from HB(C6F5)2 and (S)-tert-butylsulfinamide with ammonia borane as a hydrogen source. A variety of indolines were achieved in 40–78% yields with up to 90% ee.
使用衍生自HB(C 6 F 5)2和(S)-叔丁基亚磺酰胺的氨硼烷作为氢源,成功实现了未保护的吲哚的无金属不对称转移氢化。各种二氢吲哚的收率为40-78%,ee高达90%。
Enantioselective hydrogenation of N-heteroaromatics catalyzed by chiral diphosphine modified binaphthyl palladium nanoparticles
application of binaphthyl-stabilized palladium nanoparticles (Bin-PdNPs) with chiral modifiers in asymmetric hydrogenation of N-heteroaromatics is revealed. With an appropriate ratio of R-BINAP/Bin-PdNPs used, the pre-prepared chiral nanocatalyst achieves asymmetric hydrogenations of 2-substituted quinolines with good to excellent yields and moderate enantioselectivities, which showed superior catalytic properties