Triphenylphosphine-Thiocyanogen

Triphenylphosphine-Thiocyanogen, 333 Cyclization reactions (see Cycloaddition reactions, Ring-forming reactions, specific kinds of reactions which can be done in an intramolecular fashion) Cycloaddition reactions [2 + 2]... 

Triphenylphosphine-Thiocyanogen. The reagent is prepared by addition of Brg to lead thiocyanate suspended in CHaCU (0°) the solution of thiocyanogen is decanted and stirred with triphenylphosphine at —40". 

A general method for preparing 1,1-disubstituted thioureas in 50—80% yield employs the combined reagent triphenylphosphine-thiocyanogen (Scheme 1). ... 

Various epoxides react smoothly with the triphenylphosphine-thiocyanogen reagent to give a-thiocyanatovinyl ketones, uic-dithiocyanates, or vic-thiocyanatohydrins, depending on the structures of the epoxides used. ... 

Acylation of either pyrrole or thiophene with chlorosulfonyl isocyanate gives a 2-substituted amide which fragments on heating to give the corresponding 2-cyano derivative (Scheme 38). An alternative procedure for obtaining 2-cyanopyrrole and 3-cyanoindole involves treatment of the parent heterocycle with thiocyanogen and triphenylphosphine. 

Triphenylphosphine sulphide, (CgH5)3PS.i—Triphenylphosphine in carbon disulphide solution combines directly with sulphur to yield the sulphide, and thiocyanic acid or thiocyanogen also gives some sulphide when it reacts with the phosphine. The sulphide crystallises from alcohol in long, brilliant needles, M.pt. 150° to 151° C., readily soluble in alcohol, benzene, chloroform or carbon disulphide, insoluble in water or ether. 

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