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

Abstract

Combined use of elevated pressure in the liquid phase (15 kbar), a metal template and the sulfur nucleophilicity of [Pt 2(μ-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 [Pt 2(μ-S) 2(P–P) 2] [P–P = 2 · PPh 3; Ph 2P(CH 2) n PPh 2, 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. [Pt 2(μ-SCH 2C 6H 4CH 2S)(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 [Pt 2(μ-SCH 2C 6H 4CH 2S)(P–P) 2] 2+ for PPh 3 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.