Abstract

VILA, José L  and  BRAVO, José A. Synthesis of alkenes by fragmentation reactions; mechanistic views; the organic chemistry notebook series, a didactical approach , N² 5. Rev. Bol. Quim [online]. 2015, vol.32, n.2, pp.37-44. ISSN 0250-5460.

This is the fifth chapter in the series published by the same authors: "The Organic Chemistry Notebook Series, a Didactical Approach". Here we offer the mechanistic views of the synthesis of alkenes by fragmentation reactions. The aim of this series of studies is to help students to have a graphical view of organic synthesis reactions of diverse nature. Fragmentation reactions can conduct to the synthesis of alkenes. This is not a common method, but useful under determined conditions. For example, the fragmentation of monotoluene-p-sulphonates or methanesulphonates of suitable cyclic 1,3-diols is reviewed and the corresponding mechanism proposed. The preparation of E-cyclodecenone and cyclodecadienes by fragmentation of substituted decalylboranes is also described mechanistically. The description of the fragmentation of bicyclic compounds to afford alkenes like macrolides from acetaltosylate is also included here. The preparation of acyclic alkenes from cyclic precursors is also mechanistically described here. We have used a series of reactions reviewed by W. Carruthers, and we have proposed didactical and mechanistic views for them. This latest approach is included in the synthetic methods reviewed by W. Carruthers with respect to the "Formation of carbon-carbon double bonds".

Keywords : Organic Chemistry; Fragmentation reaction; oxidative decarboxylation; carboxylic acids; Alkenes; Mechanisms of Reactions.

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