Chugaev reaction

Chugaev reaction glacial acetic acid plus acetyl eosin-red greenish yellow 1 80,000 sensitivity... 

The Chugaev reaction, or thermal decomposition of the substituted esters of the xanthates, gives olefins without rearrangement (35,36). For example ... 

Kinetics data and Airhenius paiameteis for the Chugaev reaction are given in Reference 37. 

This mechanism of a -elimination reaction is supported by experimental findings with " S- and C-labeled starting materials." The Chugaev reaction is analogous to the ester pyrolysis, but allows for milder reaction conditions—i.e. it occurs at lower temperatures. It is less prone to side reactions, e.g. the formation of rearranged products, and is therefore the preferred method. 

The Chugaev elimination is of synthetic value, because it proceeds without rearrangement of the carbon skeleton. Other non-thermolytic elimination procedures often lead to rearranged products, when applied to the same substrates. However applicability of the Chugaev reaction is limited if the elimination is possible in more than one direction, and if a /3-carbon has more than one hydrogen. Complex mixtures of isomeric olefins may then be obtained. For example the thermolysis of xanthate 12, derived from 3-hexanol yields 28% S-hex-3-ene 13, 13% Z-hex-3-ene 14, 29% -hex-2-ene 15 and 13% Z-hex-2-ene 16 ... 

The pyrolysis of xanthates (84)—the Chugaev reaction—and of carboxylic esters (85) differ from the above in proceeding via six-membered, cyclic transition states, e.g. (86) and (87), respectively ... 

Upon thermolysis of xanthates (xanthogenates) 1 olefins 2 can be obtained, together with gaseous carbon oxysulfide COS 3 and a thiol RSH 4. This decomposition process is called the Chugaev reaction, another common transcription for the name of its discoverer is Tschugaeff. 

Chugaev reaction, 268 Cisoid conformation, 197, 344, 350 Claisen ester condensation, 229 Claisen rearrangement, 355 Claisen-Schmidt reaction, 226 Clemmensen reduction, 146 Colour... 

Studies in stereochemistry. IV. The Chugaev reaction in the determination of configuration of certain alcohols. J. Amer. chem. Soc. 71, 3883 (1949). 

Further studies on the Chugaev reaction and related reactions. J. 

Thiocarbonyl compounds for which the C=S group is linked to two heteroatoms, as in thionocarbonates, thionocarbamates, thioureas and trithiocarbonates, have been in general less directly involved as intermediates in synthesis, and we have considered here only xanthates which intervene in the Chugaev reaction (see Section 3.1) and Barton radical reactions (see Section 3.2). They are traditionally prepared by reaction of an alkoxide anion, generated from the alcohol and a strong... 

The Chugaev reaction [169], involving pyrolysis of a xanthate by an Ej mechanism, is a classical method for olefins. 

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