Olefin Syntheses by Dehydrogenation and Other Elimination Reactions

3 Olefin Syntheses by Dehydrogenation and Other Elimination Reactions 

Classic procedures for C—C double bond formation involve -elimination of two vicinal substituents X and Y from a C—C single bond. 

Z carbonyl, vinyl, aryl SeOg, PhSeBr quinones 

IfX = Y = H, the reaction is called dehydrogenation. Synthetically useful are dehydro-  

Regioselectivity of C—C double bond formation can also be achieved in the reductiv or oxidative elimination of two functional groups from adjacent carbon atoms. Well estab lished methods in synthesis include the reductive cleavage of cyclic thionocarbonates derivec from glycols (E.J. Corey, 1968 C W. Hartmann, 1972), the reduction of epoxides with Zn/Nal or of dihalides with metals, organometallic compounds, or Nal/acetone (seep,156f.), and the oxidative decarboxylation of 1,2-dicarboxylic acids (C.A. Grob, 1958 S. Masamune, 1966 R.A. Sheldon, 1972) or their /-butyl peresters (E.N. Cain, 1969). 

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Olefin Syntheses by Dehydrogenation and Other Elimination Reactions 139 Table 3, (Continued)... 

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