title: Palladium Catalyzed Cyclopropanation of Unsaturated Endoperoxides. A New Peroxide Preserving Reaction.
abstract: Unsaturated bicyclic endoperoxides are efficiently cyclopropanated with excess diazomethane in the presence of catalytic Pd(OAc)2in a stereoselective manner. This method represents a new peroxide preserving transformation. Whereas the unsaturated endoperoxides in the [2.2.1] series are attacked by the carbene from theexoface, the analogs with larger bridges are preferentially attacked from the facesynto the peroxo bridge. Only in the case of the benzannelated [2.2.2] system the attack occurs exclusively from the face proximal to the benzene ring. Certain strained cyclopropanated endoperoxides are reduced by diazomethane to givecis-diols. 1-Methylfuran endoperoxide gives rise tocis-1-formyl-2-acetylcyclopropane in excellent yield.
authors: San Francisco State University, Department of Chemistry and Biochemistry, 1600 Holloway Avenue, San Francisco, CA 94132, USA.
authors: Michael A
authors: MA
authors: Emerzian
authors: William
authors: W
authors: Davenport
authors: Jiangao
authors: J
authors: Song
authors: Jim
authors: J
authors: Li
authors: Ihsan
authors: I
authors: Erden
keywords: Cyclopropanation; Diazomethane; Palladium; Singlet oxygen; Stereoselectivity
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