YNENYLCARBENE COMPLEXES FROM ALKYNYLCARBENE COMPLEXES AND ELECTRON-RICH ALKYNES

The alkoxy(phenylethynyl)carbene]pentacarbonyl complexes, (CO)5M[C(OR)CCPh] (1) [M = W, R = Me (a), Et (b); M = Cr, R = Me (c)], react with bis(diethylamino)ethyne, diethylaminopropyne, and methylthiopropyne, respectively, to give inenyl-carbene complexes, (CO)5M{C(R1)[C(R2) = C(OR)CCPh]} (R1 = NEt2, R2 = NEt2, Me; R1 = MeS, R2 = Me), by insertion of the CC bond of the alkyne into the metal-carbene bond. The reaction is stereoselective. The structure of (CO)5W{C(NEt2)[C(NEt2)CCPh]} was established by an X-ray diffraction study. © 1990.