Regioselectivity in Reactions between Bis(2-benzothiazolyl)ketone and Vinyl Grignard Reagents: C- versus O-alkylation-Part III.

Author(s) Boga, C.; Bordoni, S.; Casarin, L.; Micheletti, G.; Monari, M.
Journal Molecules
Date Published 2018 Jan 15
Abstract

The reaction between bis(2-benzothiazolyl)ketone and vinyl Grignard reagents bearing different substituents on the vinyl moiety gave the product derived from attack on the carbonylic carbon- and/or oxygen-atom. The regioselectivity of the attack depends on the kind of substituents bound to the vinylic carbon atoms and on their relative position. The reaction between vinylmagnesium bromide and 2-methyl-1-propenylmagnesium bromide was carried out under different experimental conditions and in the presence of radical scavengers. The results indicate a plausible mechanistic pathway involving radical intermediates in the case of O-alkylation, but a polar ones in the case of classic C-alkylation. This agrees with our previous reports indicating a key role played by the delocalization ability of the substituents bound to the carbonyl group in driving the regioselectivity of the vinylmagnesium bromide attack towards O-alkylation. Further support of this was obtained by diffractometric analysis of four distinct bis(heteroaryl)ketones.

DOI 10.3390/molecules23010171
ISSN 1420-3049
Citation Boga C, Bordoni S, Casarin L, Micheletti G, Monari M. Regioselectivity in Reactions between Bis(2-benzothiazolyl)ketone and Vinyl Grignard Reagents: C- versus O-alkylation-Part III. Molecules. 2018;23(1).

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