Formation of Organometallic Heterocycles by S ‐alkylated and N‐alkylated Ruthenium Vinylidene Complexes

Treatment of [Ru]C=CPh ( 1 , [Ru] = (η 5 ‐C 5 H 5 )(dppe)Ru, dppe = Ph 2 PCH 2 CH 2 PPh 2 ) with PhN=C=S at room temperature affords the [2 + 2] cycloaddition product ( 2 ) which contains a four‐membered‐ring heterocycle. A series of cationic S‐alkylated ruthenium vinylidene complexes [Ru]=C=C(Ph)C(=NPh)SCH 2 R + ( 3a , R = CONH 2 ; 3b , R = CH=CH 2 ; 3c , R = p ‐C 6 H 4 CF 3 ) and N‐alkylated ruthenium vinylidene complexes [Ru]=C=C(Ph)C(=S)N(Ph)CH 2 R + ( 4b , R = CH=CH 2 ; 4c , R = p ‐C 6 H 4 CF 3 ) are prepared from 2 with organic halides at room temperature with high yields. Deprotonation of 3a and 3c by n ‐Bu 4 NOH in acetone induces novel cyclization reactions via C‐C bond formation and yields neutral five‐membered‐ring heterocyclic complexes ( 5a , R = CONH 2 ; 5c , R = p ‐C 6 H 4 CF 3 ). In a similar manner, deprotonation of 4b and 4c by NaOMe in CH 2 Cl 2 also induces another cyclization to yield the pyrrole‐2‐thione complexes ( 6b , R = CH=CH 2 ; 6c , R = p ‐C 6 H 4 CF 3 ). At room temperature, 5c isomerizes to the 2‐aminothiophene complex ( 7c ) in solution.