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

Abstract

Treatment of [Ru]C≡CPh (1 , [Ru] = (η5-C5H5)(dppe)Ru , dppe =Ph2PCH2CH2PPh2 ) with PhN=C=S at room temperature affords the [2 + 2] cycloaddition product [Ru]-C=C(Ph)C(=NPh)S (2) which contains a four-membered heterocycle. A series of cationic S-alkylated ruthenium vinylidene complexes [Ru]=C=C(Ph)C(=NPh)SCH2R+ (3a, R = CONH2 ; 3b, R = CH=CH2 ; 3c, R = p-C 6 H 4 CF 3 ) and N-alkylated ruthenium vinylidene complexes[Ru]=C=C(Ph)C(=S)N(Ph)CH2R+ (4b, R = CH=CH2 ; 4c, R = p-C6H4CF) are prepared from 2 with organic halides at room temperature with high yields.Deprotonation of 3a and 3c by n-Bu4NOH in acetone induces novel cyclization reactions via C-C bond formation and yields neutral five-membered heterocyclic complexes [Ru]-C=C(Ph)C(=NPh)SCHR (5a, R = CONH2; 5c, R = p-C6H4CF3). In a similar manner, deprotonation of 4b and 4c by NaOMe in CH2Cl2 also induces another cyclization to yield the pyrrole-2-thione complexes [Ru]C=C(Ph)C(=S)N(Ph)CHR (6b, R = CH=CH2 ; 6c, R = p-C6H4CF3 ). At room temperature , 5c isomerizes to the 2-aminothiophene complex [Ru]-C=C(P-C6H4CF3)SC(NHPh)=C(Ph) (7c) in solution.