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Palladium‐Catalyzed Cyclopropanation of Unsaturated Endoperoxides. A New Peroxide‐Preserving Reaction
Author(s) -
Emerzian Michael A.,
Davenport William,
Song Jiangao,
Li Jim,
Erden Ihsan
Publication year - 2009
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200800804
Subject(s) - cyclopropanation , chemistry , diazomethane , palladium , catalysis , carbene , bicyclic molecule , peroxide , yield (engineering) , medicinal chemistry , stereoselectivity , benzene , benzoyl peroxide , octene , stereochemistry , organic chemistry , materials science , polymer , ethylene , metallurgy , polymerization
Unsaturated bicyclic endoperoxides are efficiently cyclopropanated with excess diazomethane in the presence of catalytic palladium(II) acetate [Pd(OAc) 2 ] in 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 the exo face, the analogs with larger bridges are preferentially attacked from the face syn to the peroxo bridge. Only in the case of the benzannelated [2.2.2] system does the attack occur exclusively from the face proximal to the benzene ring. Certain strained cyclopropanated endoperoxides are reduced by diazomethane to give cis ‐diols. 2‐Methylfuran endoperoxide gives rise to cis ‐1‐formyl‐2‐acetylcyclopropane in excellent yield.