Thiomethylation, Nitro Reduction and Tandem Reduction/SMe Insertion of Nitrogen Heterocycles Using BF3⦁SMe2

Herein, a general, solvent-free and straightforward thiomethylation of electron deficient heterocycles using BF3⦁SMe2 as a dual thiomethyl source and Lewis acidic activator is presented. A range of heterocycles including pyrimidine, pyrazine, pyridazine, thiazole and purine derivatives were successfully substituted using this method. An unexpected reductive property of BF3⦁SMe2 towards nitropyridines was also discovered including an intriguing tandem reduction/SMe insertion process in certain substrates. Notable features of the present work include its convenience and use of a non-malodorous reagent while the discovery of novel chemical transformations using BF3⦁SMe2 provides fundamental new insights into the reactivity of this commonly employed reagent.