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 [Pt2(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 [Pt2(μ-S)2(P-P) 2] [P-P = 2 • PPh3; Ph2P(CH 2)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(μ-SCH2C6H 4CH2S)(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(μ-SCH 2C6H4CH2S)(P-P)2] 2+ for PPh3 and dppp have been isolated as PF6- 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. © 2005 Elsevier B.V. All rights reserved.