Rhodium(I)‐Catalyzed Intramolecular Carbonylative [2+2+1] Cycloadditions and Cycloisomerizations of Bis(sulfonylallene)s

Novel [{RhCl(CO)dppp} 2 ]‐catalyzed intramolecular carbonylative [2+2+1] cycloadditions of bis(phenylsulfonylallene) derivatives under CO, leading to the facile formation of bis(phenylsulfonyl)bicyclo[ n .3.0] frameworks ( n =4–6), have been developed. The terminal double bonds of both allenyl moieties served exclusively as the two π‐components. In particular, this newly developed method was shown to be a powerful tool for the construction of bicyclo[6.3.0]undecadienones, which have hardly been prepared by the known Pauson–Khand (‐type) reactions. The bicyclo[7.3.0]dodecadienone homologue (one extra carbon) could be formed in rather low yields. Alternatively, novel cycloisomerizations of bis(phenylsulfonylallene) derivatives with catalysis by the same Rh I complex under N 2 readily produced the 3,4‐dimethylene‐2,5‐bis(phenylsulfonyl)cyclononene and the corresponding cyclooctene and cycloheptene frameworks.