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A Family of Well-Defined Chiral-at-Cobalt(III) Complexes as Metal-Templated Hydrogen Bond Donor (HBD) Catalysts: Effect of Chirality at Metal Center on Stereochemical Outcome of Reactionстатья Научно-популярная статья
Статья опубликована в высокорейтинговом журнале
Статья опубликована в журнале из списка Web of Science и/или ScopusДата последнего поиска статьи во внешних источниках: 1 апреля 2022 г.
- Авторы: Khromova Olga V., Emelyanov Mikhail A., Smolyakov Alexander F., Fedyanin Ivan V., Maleev Victor I., Larionov Vladimir A.
- Журнал: Inorganic Chemistry
- Том: 61
- Номер: 14
- Год издания: 2022
- Издательство: American Chemical Society
- Местоположение издательства: United States
- Первая страница: 5512
- Последняя страница: 5523
- DOI: 10.1021/acs.inorgchem.1c03927
- Аннотация: A family of well-defined Λ- and Δ-diastereomeric octahedral cationic chiral-at-cobalt complexes were obtained by a simple two-step reaction of (R,R)-1,2-diaminocyclohexane, (R,R)-1,2-diphenylethylenediamine or (S)-2-(aminomethyl)pyrrolidine and substituted salicylaldehydes with a cobalt(III) salt. It was observed for the first time that the use of an excess of Co(III) salt provides both the enantiopure Λ- and Δ-forms of the corresponding Co(III) complexes 1-2 in a ratio of diastereomers ranging from 1:1.6 to >20:1 (Λ/Δ) and in 31–95% combined yields. The obtained complexes are robust, air- and bench-stable, soluble in most of organic solvents and insoluble in water. By varying the substituents in phenyl ring of salicylaldehyde moiety was shown that both steric and electronic effects of substituents have a significant impact on the formation of Λ- and Δ-isomers. Next, the efficacies of the enantiopure metal-templated complexes 1-3 were investigated in three benchmark asymmetric reactions in order to compare their catalytic activity. The chiral Co(III) complexes 1-3 have been tested as enantioselective HBD catalysts in such important reactions as Michael addition of O’Donnell substrate to methyl acrylate, epoxidation of chalcone and trimethylsilylcyanation of benzaldehyde. It was clearly demonstrated that the chirality at cobalt center has an impact on stereochemical outcome of the reactions. In particular, Λ(R,R)-1 and Δ(R,R)-1 complexes acted as “pseudo-enantiomeric” catalysts in epoxidation and trimethylsilylcyanoation reactions providing both enantiomers of the products with up to 57% ee.
- Добавил в систему: Ларионов Владимир Анатольевич
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