STEREOSPECIFIC SYNTHESIS OF ALKENES FROM 1,2-DIOLS; MECHANISTIC VIEWS; THE ORGANIC CHEMISTRY NOTEBOOK SERIES, A DIDACTICAL APPROACH, Nº 8

Abstract

"The aim of this series of studies is to help students to have a graphical view of organic synthesis reactions of diverse nature. Here we discuss, from a mechanistic stand point, some methods for the stereospecific synthesis of alkenes from 1,2-diols. One of the best ones utilizes as precursors, the cyclic thionocarbonates obtained from the diol with thiophosgene. We describe by mechanisms, the use of 1,3-dimethyl-2-phenyl-1,3,2 diazophospholidine as an alternative for the decomposition of thionocarbonates into alkenes. We discuss by mechanisms, a general and unambiguous method for the interconversion of Z- and E-alkenes. Thus, the conversion of the (Z)-cyclooctene into the E isomer is detailed here. The mechanism of the conversion of meso-1,4-diphenylbutan 2,3-diol into (Z)-1,4- diphenyl-2-butene is here described. We have used various series of reactions reviewed by W. Carruthers in ‘Some modern methods of organic synthesis’, and we have proposed didactical and mechanistic views for them. This theme is included in the chapter “Formation of carbon-carbon double bonds” in the text mentioned above."