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Rhodium(I)-Catalyzed Cyclization of Allenynes with a Carbonyl Group through Unusual Insertion of a C[DOUBLE BOND]O Bond into a Rhodacycle Intermediate


  • This work was supported in part by Grants-in-Aid for Scientific Research (B) (No. 23390001) from the Japan Society for the Promotion of Science (JSPS) and by a Grant-in-Aid for Scientific Research on Innovative Areas “Molecular Activation Directed toward Straightforward Synthesis (No. 25105701)” from MEXT (Japan). A.H. thanks JSPS for providing a Research Fellowship for Young Scientists.


Rhodium(I)-catalyzed cyclization of allenynes with a tethered carbonyl group was investigated. An unusual insertion of a C[DOUBLE BOND]O bond into the C(sp2)–rhodium bond of a rhodacycle intermediate occurs via a highly strained transition state. Direct reductive elimination from the obtained rhodacyle intermediate proceeds to give a tricyclic product containing an 8-oxabicyclo[3.2.1]octane skeleton, while β-hydride elimination from the same intermediate gives products that contain fused five- and seven-membered rings in high yields.