An Unprecedented [C2+C1+C1] Coupling of an Alkynyl, an Allenylidene, and a CO Unit: The Formation of a Highly Unsaturated Cyclobutenone Derivative in the Coordination Sphere of Rhodium(I)

Mono- and dinuclear organometallic rhodium(I) complexes such as 1 are obtained in excellent yields by the reaction of trans-[RhF{=C=C=C(Ph)R}(PiPr3)2] with triphenylstannanes PhC≡CSnPh3 and Ph3SnC≡CC≡CSnPh3. Compound 1 undergoes an unprecedented [C2+C1+C1] coupling reaction with CO to produce the highly unsaturated cyclobutenone derivative 2. R=Ph, tBu; L=iPr3.