Palladium-Mediated Intramolecular Formation of a C-S Bond: Application to the Selective Syntheses of Six- and Seven-Membered Sulfur-Containing Heterocycles

Article abstract of DOI:10.1021/jo00109a036

Cyclopalladated complexes derived from benzylmethyl sulfide, o-iodo sulfides, or methyl-2-biphenyl sulfide react with alkynes to give stable organometallic compounds whereby the alkyne has inserted in the carbon-palladium bond.Activation of these complexes was effected by treatment with a silver salt, and resulting thermolysis led to a selective depalladation process, affording a series of both neutral and cationic 1H-2S-benzothiopyran derivatives.With dissymmetric alkynes this reaction displayed a high degree of regiocontrol.Under similar conditions, a new entry for the synthesis of derivatives of the rare family of dibenzothiepins was achieved.