Synthesis and Metal-Catalyzed Reactions of gem-Dihalovinyl Systems

A systematic summary of methods for the synthesis of 1,1-dihaloolefins is presented. An overview of metal-catalyzed reactions involving these compounds and leading to the formation of new C-C, C-H, C-N, bonds, by an effective replacement of one or both dihalides with other elements, is also presented. Taylor and co-workers have developed a practical one-pot synthesis of 1,1-dibromoalkenes from primary alcohols via manganese dioxide-mediated oxidation and the subsequent Wittig reaction. Burton and co-workers studied the dichloromethylenation of substituted cyclohexanones with CXCl 3 and PPh 3 under a variety of conditions. In 1999, Amii and Uneyama reported that metallic magnesium, which serves as a convenient electron source, proved to be useful for the C-F bond breaking process of trifluoromethyl ketones to provide a practical route to 2,2-difluoroenol silyl ethers. Shi and Huang studied the fluoride-mediated nucleophilic reactivity toward aromatic aldehydes of the CF 2-containing reagent.