NEW UNSATURATED CYCLIC CARBENES VIA DIRECT ACTIVATION OF ENYNOLS BY RUTHENIUM(II) COMPLEXES

RuCl2(PMe(3))(C(6)Me(6)) (3) reacts with (Z)-HC=CC(Me)=CHCH2OH (1) in the presence of NaPF6 to afford a cyclic alpha,beta-unsaturated carben e, the 2-oxacyclohex-5-en-1-ylidene ruthenium complex 4, and the react ion of RuCl(PMe(3))(2)(C(5)Me(5)) (5) with both 1 and its E isomer 2 b eads to the same six-membered unsaturated carbene complex 6. The activ ation of (Z)-HC=CC(Me)=CHCH(R)OH derivatives (R=Me (7), C=CSiMe(3) (9) ) with 5 affords the carbene complexes 8 and 10, and their formation i s explained on the basis of a Ru=C=C=C(Me)CH2CH(R)OH allenylidene inte rmediate.