The Copper-Catalyed Intramolecular C-S Coupling Of Vinyl Bromides

Many biologically active compounds contain cyclic sulfides, such as penicillins, cephalosporins, biotin, etc. Furthermore, some polymers also have this structure. Cyclic sulfides are promising synthetic intermediates. We herein investigated the copper-catalyed intramolecular S-vinylation of bromothiols leading to the synthesis of 2-methylenethietanes.The synthesis of 2-methylenethietanes via copper-catalyzed intramolecular coupling of thiols with vinyl bromides was investigated in this paper. Many factors which affect the reaction, including the reaction temperature, the reaction time, the amount of catalyst used, bases, ligands, as well as the solvent, were studied .The optimal reaction conditions of reation was that: Under nitrogen atmosphere, with 10 mol% CuI as the catalyst, 20 mol% triphenylphosphine as the ligand and 2 equivalents of K₃PO₄·3H₂O as the base, the reaction of 2-bromoundec-1-ene-4-thiol in refluxing CH₃CN (0.1 M), led to the convenient formation of the corresponding 2-heptyl-4-methylenethietane in good yields via a 4-exo ring closure.With the optimized conditions in hand, we then examined the scope of this methodology and excellent results were achieved.