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Selective Cross‐Coupling of Unsaturated Substrates on Al I
Author(s) -
Dmitrienko Anton,
Pilkington Melanie,
Nikonov Georgii I.
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202004907
Subject(s) - chemistry , ketone , medicinal chemistry , pyridine , substituent , moiety , benzophenone , adduct , isophorone , isopropyl , aniline , imine , alkoxide , thiophenol , coupling reaction , ligand (biochemistry) , stereochemistry , photochemistry , organic chemistry , catalysis , biochemistry , receptor
Abstract The Al I compound NacNacAl ( 1 , NacNac = [ArNC(Me)CHC(Me)NAr] − , Ar = 2,6‐ i Pr 2 C 6 H 3 ) serves as a template for the chemoselective coupling between carbonyls (benzophenone, fenchone, isophorone, p ‐tolyl benzoate, N , N ‐dimethylbenzamide, (1‐phenylethylidene)aniline) and pyridine. With the CH‐acidic ketone (1 R )‐(+) camphor, the reaction affords a hydrido alkoxide compound of Al, formed as the result of enolization, whereas an enolizable imine, (1‐phenylethylidene)aniline, and the bulky ketone isophorone, still chemoselectively couple with pyridine. In contrast, reaction with the ester p ‐tolyl benzoate results in cleavage of the ester bond together with replacement of the alkoxy group by a hydrogen atom of the pyridine moiety. This study demonstrates that for carbonyl substrates featuring phenyl substituents, the reaction proceeds via intermediate formation of η 2 (C,X)‐coordinated (X = O, N) carbonyl adducts, whereas the reaction of 1 with ( R )‐(−)‐fenchone in the absence of pyridine leads to CH activation in the pendant isopropyl group of the Ar substituent of the NacNac ligand.