On the development of a nucleophilic methylthiolation methodology

Methylthiolation reactions are usually explored to access organosulfur compounds using methanethiol, an extremely flammable and toxic compound. Herein, methylthiomethyl esters were successfully applied as novel methylthiolation reagents in a low cost, transition-metal-free methodology. These reagent...

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Bibliographic Details
Published in:Organic & biomolecular chemistry 2020-07, Vol.18 (28), p.542-5426
Main Authors: Carvalho, Bernardo Basbaum Portinho de Puga, Amaral, Adriane Antonia Pereira, de Castro, Pedro Pôssa, Ferreira, Fernanda Cerqueira Moreira, Horta, Bruno Araújo Cautiero, Amarante, Giovanni Wilson
Format: Article
Language:English
Subjects:
Acetates
Acetic acid
Density functional theory
Enthalpy
Esters
Flammability
Infrared spectroscopy
Intermediates
Mathematical analysis
Methanethiol
NMR
Nuclear magnetic resonance
Organosulfur compounds
Reaction mechanisms
Reagents
Transition metals
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Summary:Methylthiolation reactions are usually explored to access organosulfur compounds using methanethiol, an extremely flammable and toxic compound. Herein, methylthiomethyl esters were successfully applied as novel methylthiolation reagents in a low cost, transition-metal-free methodology. These reagents allowed the methylthiolation of a wide scope of chalcones, acyl ester derivatives and Morita-Baylis-Hillman acetates with good group tolerance, affording the methylthiolated products in moderate to excellent yields. The reaction mechanism was investigated through several control experiments, as well as by theoretical calculations employing Density Functional Theory. The results strongly support that a sulfurane and a sulfonium ylide appear as key intermediates and that a Pummerer type rearrangement is also crucial for the formation of this novel reagent. Furthermore, the methylthiolation mechanism is likely to proceed through the nucleophilic attack of the reagent, followed by an entropically favoured step involving the acetate attack to the positively charged species, then releasing the product. A novel nucleophilic methylthiolation method is described. This process allows a diversity of either conjugate additions or substitutions reactions in order to incorporate CH 3 S- group into activated carbons.
ISSN:1477-0520
1477-0539
DOI:10.1039/d0ob01149e