title: Rh-catalyzed Reagent-Free Ring Expansion of Cyclobutenones and Benzocyclobutenones.
abstract: Here we report a reagent-free rhodium-catalyzed ring-expansion reaction via C-C cleavage of cyclobutenones. A variety of poly-substituted cyclopentenones and 1-indanones can be synthesized from simple cyclobutenones and benzocyclobutenones. The reaction condition is near pH neutral without additional oxidants or reductants. The potential for developing a dynamic kinetic asymmetric transformation of this reaction has also been demonstrated. Further study supports the proposed pathway involving Rh-insertion into the cyclobutenone C-C bond, followed by β-hydrogen elimination, olefin insertion and reductive elimination.
authors.affiliation: The University of Texas at Austin, Department of Chemistry, Austin, TX 78712, United States.
authors.forename: Peng-Hao
authors.initials: PH
authors.lastname: Chen
authors.affiliation: Department of Chemical Development, Boehringer Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Road/P.O. Box 368, Ridgefield, Connecticut 06877-0368, United States.
authors.forename: Joshua
authors.initials: J
authors.lastname: Sieber
authors.affiliation: Department of Chemical Development, Boehringer Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Road/P.O. Box 368, Ridgefield, Connecticut 06877-0368, United States.
authors.forename: Chris H
authors.initials: CH
authors.lastname: Senanayake
authors.affiliation: The University of Texas at Austin, Department of Chemistry, Austin, TX 78712, United States.
authors.forename: Guangbin
authors.initials: G
authors.lastname: Dong