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Bis-Cyclometalated Indazole Chiral-at-Rhodium Catalyst for Asymmetric Photoredox Cyanoalkylations.

ABSTRACT: A new class of bis-cyclometalated rhodium(III) catalysts containing two inert cyclometalated 6-tert-butyl-2-phenyl-2H-indazole ligands and two labile acetonitriles is introduced. Single enantiomers (>99?%?ee) were obtained through a chiral-auxiliary-mediated approach using a monofluorinated salicyloxazoline. The new chiral-at-metal complex is capable of catalyzing the visible-light-induced enantioselective ?-cyanoalkylation of 2-acyl imidazoles in which it serves a dual function as the chiral Lewis acid catalyst for the asymmetric radical chemistry and at the same time as the photoredox catalyst for the visible-light-induced redox chemistry (up to 80?% yield, 4:1?d.r., and 95?%?ee, 12?examples).

SUBMITTER: Steinlandt PS

PROVIDER: S-EPMC6916287 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Bis-Cyclometalated Indazole Chiral-at-Rhodium Catalyst for Asymmetric Photoredox Cyanoalkylations.

Steinlandt Philipp S PS Zuo Wei W Harms Klaus K Meggers Eric E

Chemistry (Weinheim an der Bergstrasse, Germany) 20191113 67

A new class of bis-cyclometalated rhodium(III) catalysts containing two inert cyclometalated 6-tert-butyl-2-phenyl-2H-indazole ligands and two labile acetonitriles is introduced. Single enantiomers (>99 % ee) were obtained through a chiral-auxiliary-mediated approach using a monofluorinated salicyloxazoline. The new chiral-at-metal complex is capable of catalyzing the visible-light-induced enantioselective α-cyanoalkylation of 2-acyl imidazoles in which it serves a dual function as the chiral Le ...[more]

PMID: 31541505

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