Oxyfunctionalization of CH2-Group Activated by Adjacent Three-Membered Ring

Abstract

Background: Increasing use of the three-membered ring in drug development initiates the search for efficient methods of transformations of cyclopropane derivatives. Oxidation of methylene group activated by an adjacent cyclopropane represents a direct approach towards carbonylcyclopropanes, allows avoiding unnecessary synthetic stages and meets the requirements of atom economy. Objective: In this review all available data concerning the oxidation of cyclopropane-containing hydrocarbons and their functionally substituted derivatives are systematized, and the general regularities between the structure of the starting compound, the oxidant employed and the reaction outcome are underlined. Conclusion: The following regularities were distinguished for the oxidation of cyclopropane-containing compounds into cyclopropylketones. The main structural parameters of the starting compounds, which influence the distribution of the oxidation products, are the followings: the presence of competing C-H bonds, flexibility or rigidity of structure, electron and sterical substituents effects. A number of preparative methods of activated C(sp3)-H bonds oxygenation were elaborated, employing such powerful oxidants as ozone, dioxiranes, CrO3 and a variety of catalytic systems, based on transition metals. For the oxidation of cyclopropane derivatives all these oxidants may be employed. RuO4, generated in situ, usually behaves as selective and soft oxidant. TFDO often demonstrates lesser selectivity, but it may be the best choice when several activated CH2 groups should be oxidised. In the case of dihalocyclopropanes the use of CrO3 is preferable. Summarily, the oxidation of methylene group adjacent to cyclopropane has been undoubtedly developed into a reliable preparative approach to cyclopropylketones, which should find an active use in synthetic organic chemistry.