COMMUNICATIONS the significant contribution from a metallacyclo-3-pentene resonance form in the resultant q4 complex. We are currently examining further utilization of the potential of vinylallenes in reactions with transition metal catalysts proceeding through q4 complexes.
Experiixentd Procedure3: To a solution of (E)-4-phenyl-5-(trimethylsilyl)-l,2,4-pentatriene (Za. 25 my. 0.12 mmnl) in benzene (3 mL) at room temperature was added [RhCI(PPh,),] (129 mg, 0.139 mmol). After the mixture was stirred for 13 h, the solvent was removed under vacuum. The residue was subjected to column chromatography (silica gel, CH,CI,.hexane = 3.1) to afford 3 (80 mg, 78%) as a yellow powder. 4. To a solution of (€)-5-methyl-2-phenyl-l-(trimethylsilyl)-l,3.4-hexatriene (Zb, 40 mg. 0.165 mmol) in benzene (4 mL) at room temperature was added [RhCI-(PPh,),] (153 mg. 0.165 mmol). After the mixture was stirred for 20 h, the solvent was removed under vacuum. The residue was subjected to preparative thin-layer chromatography (silica gel, CH,CI,:hexane = 3:l) to afford end-4 (47 mg, 44%. orange powder) and eao-4 (20 mg, 19%. yellow powder).7c. 7c': A mixture of [Rh(cod),]PF, (10.9mg. 23.5 pmol), dppe (11.2 mg, 28.1 pmol). and 2c (200 mg. 1-17 mmol) in toluene (2 mL) was stirred at 80°C for 20 h under 15 atm of CO in an autoclave. After the mixture was cooled. the solvent was removed under vacuum. The residue was subjected to column chromatography (silica ge1,ether:hexane =1.10) toafford7c(130mg, 56%)and7c'(60.0mg, 26%) as colorless solids.
