Regioselective addition of chalcogenol to an η3-propargyl/allenyl complex via formation of the carbon-chalcogen bond leading to new chalcogenoxyallyl species

Article abstract of DOI:10.1016/0022-328X(96)06269-9

Regioselective addition of chalcogenol to an η³-propargyl complex [Pt(PPh₃)₂(η³-C₃H₃)](BF₄) (2) via the formation of the C-O, C-S, or C-Se bond generates new cationic chalcogenoxyallyl species {Pt(PPh₃)₂[η³-CH₂C(ER)CH₂]}(BF₄) (E = O, R = Me (4a), Et (4b), ⁱPr (4c), ^tBu (4d), Ph (4e); E = S, R = Et (5b), ⁱPr (5c), ^tBu (5d), Ph (5e); E = Se, R = Ph (6e)) respectively in good yields. Thiol and selenol react with complex 2 much faster than alcohol; and 2 reacts with p-(HO)C₆H₄(SH) to exclusively yield the thioxyallyl product {Pt(PPh₃)₂[η³-CH₂C(SC₆H₄OH)CH₂]}(BF₄) (5f). Among the alcohols and phenol, the reactivity follows the order MeOH > EtOH > ⁱPrOH > ^tBuOH > PhOH. A mechanism comprising a preceding coordination step is postulated. The X-ray structures of 4b, 4e, 5b, 5e and 6e are provided.