(Vinylallene)rhodium complexes with three kinds of coordination modes, that is, η 2-coordination of the terminal π-bond of the allenyl group, η 4-coordination of the conjugated diene skeleton, and planar σ 2-coordination, were synthesized by ligand substitution of RhCl(PPh3)3 with vinylallenes of specific substitution patterns. Their structures were determined by X-ray crystallography. Coordination preferences can be explained in terms of spatial interactions between the vinylallene substituents and the phosphine ligands as well as effective delocalization of the π-electrons of the endo- and exocyclic double bonds. The structural studies were extended to the development of the rhodium-catalyzed carbonylative [4 + 1] cycloaddition reaction of vinylallenes, affording five-membered carbocycles. With a nonsymmetrical vinylallene, face-selective η 4-coordination from the less hindered side of the allenyl group was observed. The achievement of [4 + 1] carbonylation can be attributed to (i) the substantial facility of substituted vinylallenes for η 4-coordination and (ii) the significant contribution of a metallacyclo-3-pentene resonance form to the intermediate complex. A platinum(0) complex also catalyzed the [4 + 1] cycloaddition of vinylallenes as efficiently as rhodium.

Rhodium(I) and platinum(0) complexes having a chiral ligand, 1,2-bis(2,5-dialkylphosphorano)benzene, effected an asymmetric carbonylative [4 + 1] cycloaddition reaction of vinylallenes. Useful levels of asymmetric induction were attained even with substrates lacking directive heteroatom functionalities. The highest enantioselectivity of 95.0% ee was achieved in the rhodium-catalyzed reaction of a vinylallene bearing an ester group. Whereas the enantioselectivities of the rhodium-catalyzed reactions were significantly affected by the substrate structures, the platinum-catalyzed reactions generally presented good enantioselectivities over 70% ee. In particular, the observed absolute configurations were opposite to those observed in the rhodiumcatalyzed reactions. The reversal of the induced chirality according to the center metal employed was interpreted mechanistically.

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