ACTIVATION OF 2-PROPYN-1-OL DERIVATIVES BY (ARENE)RUTHENIUM(II) COMPLEXES - NEW ROUTE TO (ALKENYLCARBENE)METAL AND (POLYENYLCARBENE)METAL COMPLEXES

Reactions of the (arene)ruthenium(II) complexes (eta(6)-arene)(PMe3)RuCl2 (arene = C6Me6 (1), C6Me4H2 (1')) with disubstituted HC = CC(R)(R')OH (R,R' = Me, Me (a), cyclohexyl (b), Ph, Ph (c)) or mono-substituted 2-propyn-1-ols HC = CC(R)(H)OH (R = Me (d), Ph (e), 2-thienyl (f)), in methanol containing NaPF6, lead to the cationic methoxyalkenylcarbene complexes [(eta(6)-arene)(PMe3)(Cl)Ru = C(OMe)(CH = CRR')]PF6 (2,2',R' not-equal H; 3, 3', R' = H) in ca. 70% yield. Difference H-1 NOE experiments establish an s-cis conformation for ((monosubstituted alkenyl)carbene)ruthenium moieties (3, 3') and an s-trans conformation in (disubstituted alkenyl)carbene complexes 2 and 2'. A crystal structure of [(eta(6)-C6Me6)-(PMe3)(Cl)Ru = C(OMe)(CH = CPh2)]PF6 (2c) has been determined by X-ray diffraction. It shows an s-trans conformation for the methoxy(diphenylalkenyl)carbene moiety. Crystal data are as follows: monoclinic, P2(1)/n, with a = 9.826 (2) angstrom, b = 15.659 (1) angstrom, c = 21.552 (2) angstrom, beta = 92.89 (1)-degrees, V = 3312.0 (6) angstrom 3, Z = 4, R = 6.9%, R(w) = 7.2%. Treatments of 1 and 1' with HC = CC(CH = CHR)(H)OH (R = Ph (g), Me (h)) and HC = CC(CH = CHCH = CHMe)(H)OH (i) produce dienylcarbene (4g,4'h) and trienylcarbene (5i, 5'i) ruthenium complexes in 70-90% yield. Reaction of 1 with HC = CCH2OH in methanol gives a double addition of MeOH and generates [(eta(6)-C6Me6)(PMe3)(Cl)Ru = C(OMe)(CH2CH2OMe)]PF6 (7). Methoxyalkenylcarbene complexes 2-5 and 2'-5' are formed via allenylidene intermediates [(eta(6)-C6Me6)(L)(Cl)-Ru = C = C = CPh2]PF6 that have been trapped during the reaction of (eta(6)-C6Me6)(L)RuCl2 (L = PMe3 (1), PPh3 (8)) with HC = CCPh2OH (c) in methanol (9c, 10c). The (allenylidene)ruthenium intermediate can be stabilized by the introduction of a ferrocenyl group at C3: reaction between HC = CC(Ph)(Fc)OH (j) and 1 in methanol only leads to the stable complex [(eta(6)-C6Me6)(PMe3)(Cl)Ru = C = C = C(Ph)(Fc)]PF6 (11j).