Easy Entry to Terminal 1,5- and 1,6-Enynes from (Indenyl)ruthenium(II) Allenylidenes and Grignard Reagents

4 páginas, esquemas.The allenylidene complexes [Ru( C C CR1R2)(η5-C9H7)(PPh3)2][PF6] (R1 = R2 = Ph (1a); R1 = H, R2 = Ph (1b), C(Me) CPh2 (1c); CR1R2 = (1R)-1,3,3-trimethylbicyclo[2.2.1]hept-2-ylidene (1d)) react with Grignard reagents CH2 CH(CH2)nMgBr (n = 1, 2) to yield the σ-alkynyl derivatives [Ru{C CCR1R2(CH2)nCH CH2}(η5-C9H7)(PPh3)2] (2a−d, 3a−c). Protonation of 2a−d and 3a−c with HBF4·Et2O leads to the vinylidene complexes [Ru{ C C(H)CR1R2(CH2)nCH CH2}(η5-C9H7)(PPh3)2][BF4] (4a−d and 5a−c), which can be easily demetalated with acetonitrile to afford the terminal enynes HC CCR1R2(CH2)nCH CH2 (6a−d and 7a−c) and the nitrile complex [Ru(N CMe)(η5-C9H7)(PPh3)2][BF4] (8).This work was supported by the Ministerio de Ciencia y Tecnología of Spain (Project BQU2000-0227) and the FICYT of Asturias (Project PR-01-GE-4).Peer reviewe