The Preparation of Olefins by the Pyrolysis of Xanthates. TheChugaev Reaction

Abstract

In this chapter the Chugaev reaction is defined as the thermal decomposition of the xanthate ester of an alcohol that contains at least one beta‐hydrogen atom to produce one or more olefins, carbon oxysulfide and a mercaptan. The formation of olefins by the pyrolysis of xanthates was discovered in 1899 by Chugaev in connection with his studies on the optical properties of xanthates and other compounds. He subsequently employed the reaction in his investigation of terpenes and demonstrated both its utility as an olefin‐forming reaction and its usefulness in structural determination. The reaction, which is particularly valuable for the conversion of sensitive alcohols to the corresponding olefins without the rearrangement of the carbon skeleton is analogous to the thermal decomposition of carboxylic esters of alcohols and other derivatives such as carbamates and carbonates, to yield olefins.

Straightforward Xanthate-Mediated Synthesis of Functional γ-Thiolactones and Their Application to Polymer Synthesis and Modification

“…Functional thiolactones are attractive reagents for the preparation of functional polymeric materials, but the lack of a simple and general procedure for their synthesis is a significant barrier to their implementation. The experimental strategy we report here (Scheme ) was inspired by the work of Zard and co-workers on free radical addition of dithiocarbonates (xanthates) to alkenes , and their thermally induced dethiocarboxylation (Chugaev elimination). − Our process involves the following consecutive steps: (i) peroxide-induced radical addition of an O -alkyl xanthate to a substituted alkene to yield the xanthate:alkene 1:1 adduct and (ii) thermolysis of the O -alkyl xanthate group to produce the corresponding thiol, which directly reacts with a leaving group (here a methyl ester) borne by the xanthate S -fragment to form a γ-thiolactone. Following this route, a great variety of R 1 functional groups can be incorporated into the thiolactone structure in the γ-position, making use of the vast range of commercially available substituted alkenes.…”

Molecular Design, Synthesis, and Biological Evaluation of 2-Hydroxy-3-Chrysino Dithiocarbamate Derivatives

“…They can undergo regioselective ring opening from the less hindered terminal carbon side of the epoxide ring with a wide variety of nucleophiles by SN 2 reaction. The dithiocarbamate nucleophiles generated in situ from CS 2 and amines open the epoxide ring from the terminal carbon side [39,40,41] to afford 2-hydroxy dithiocarbamates, which are found to have a wide variety of applications in organic synthesis [42,43,44,45], pharmaceuticals [46,47,48,49], and agriculture [50,51,52].…”

Discovery of the RAFT/MADIX Process: Mechanistic Insights and Polymer Chemistry Implications

“…By using a xanthate agent 37 bearing a sec -propyl group on the oxygen, one obtains polymers 38 which, upon heating to around 160 °C, release propene and carbon oxysulfide through the well-known Chugaev elimination (Scheme ). This simple operation removes the thiocarbonyl sulfur which is responsible for the eventual liberation of the obnoxious hydrogen sulfide upon exposure of the finished polymer to the elements in later applications . The thiol group remaining in the modified polymer 39 is relatively innocuous (human hair contains an abundance of cysteine residues and thus pendant thiols).…”