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(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(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(μ-SCH2C6H4CH2S)(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-SCH2C6H4CH2S)(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.

Graphical abstractUnder high pressure (15 kbar) at r.t., reactions of [Pt2(μ-S)2(PP)2] [P–P = 2 · PPh3; Ph2P(CH2)nPPh2, n = 2 (dppe), 3 (dppp)] with α-α′-dichloro-o-xylene would progress to a catalytic-like pathway to yield 3,8-dibenzo-1,6-dithiacyclodecane (up to 35%), and a series of mechanistically relevant intermediates and byproducts. This combined use of pressure and sulfur nucleophilicity and the templating effect of a diplatinum offer a unique possibility to prepare macrocyclic dithioether in a one-pot synthesis.Figure optionsDownload full-size imageDownload as PowerPoint slide