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Molecules 2018, 23(1), 171; https://doi.org/10.3390/molecules23010171

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

1
Department of Industrial Chemistry ‘Toso Montanari’, Alma Mater Studiorum–Università di Bologna Viale Del Risorgimento 4, 40136 Bologna, Italy
2
Department of Chemistry ‘Giacomo Ciamician’, Alma Mater Studiorum–Università di Bologna Via Selmi 2, 40126 Bologna, Italy
Parts 1 and 2 are references 10 and 12, respectively.
*
Authors to whom correspondence should be addressed.
Received: 20 December 2017 / Revised: 10 January 2018 / Accepted: 12 January 2018 / Published: 15 January 2018
(This article belongs to the Collection Heterocyclic Compounds)
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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. View Full-Text
Keywords: bis(2-benzothiazolyl)ketone; Grignard reagents; vinylmagnesium bromide; C-alkylation; O-alkylation bis(2-benzothiazolyl)ketone; Grignard reagents; vinylmagnesium bromide; C-alkylation; O-alkylation
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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, 171.

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