Combinative use of high-pressure, metal-templating and sulfur-nucleophilicity towards dithiacyclophane synthesis and its complex intermediates

Combined use of elevated pressure in the liquid phase (15 kbar), a metal template and the sulfur nucleophilicity of [Pt₂(l-S)₂-(P–P)₂] (P–P = diphosphine or 2 . monophosphine) facilitates the one-pot synthesis of 3,8-dibenzo-1,6-dithiacyclodecane. Under r.t.p., nucleophilic addition of [Pt₂(l-S)₂(P–P)₂] [P–P = ₂ . PPh₃; Ph₂P(CH₂)_nPPh₂, n = 2, 1,2-bis(diphenylphosphino)ethane (dppe), 3, 1, 3-bis(diphenylphosphino)propane (dppp)] with α-α′ -dichloro-o-xylene would terminate as a dithiolato bridged cation viz. [Pt₂(lSCH₂C₆H₄CH₂S)(P–P)₂] ²⁺. Under high pressure (15 kbar) at r.t., these stoichiometric reactions progress via a ‘‘catalytic-like’’ pathway to yield 3,8-dibenzo-1,6-dithiacyclodecane (up to 35%), and a series of mechanistically relevant intermediates and byproducts. The dithiolated intermediates [Pt₂(l-SCH₂C₆H₄CH₂S)(P–P)₂] ²⁺ for PPh₃ and dppp have been isolated as PF^-₆ complexes and their crystal structure determined. The formation of 3,8-dibenzo-1,6-dithiacyclodecane demonstrates a convenient synthetic strategy over the multi-step synthesis of this macrocyclic dithioether.