Desulfonylation reactions

The ten-membered cyclic amine 106 was efficiently prepared from quionolizidine derivative 105 by methylation to a nonisolated intermediate followed by an olefin-forming desulfonylation reaction induced by treatment with sodium amalgam (Scheme 11) <20010L2957>. 

Dess-Martin Oxidation, 53, 1 Desulfonylation reactions, 72, 2 Desulfurization ... 

As models for the investigation of the S i and S i mechanisms the thermal decompositions of alkyl chlorosulfites and allyl chlorosulfites have received considerably more attention than that of other desulfonylation reactions. The usual method of converting alcohols into alkyl chlorides is by treatment with thionyl chloride. This reaction has been shown to proceed through an alkyl chlorosulfite which can often be isolated and shown to decompose by a homogeneous first-order process yielding alkyl chloride and 802 " , although frequently substantial amounts of alkene are formed in the reaction , viz. 

J. L. Kice, Desulfonylation Reactions, Chapter 5, The Chemistry of Organic Sulfur Compounds, Volume 2, Ed. N. Kharasch and C. Y. Meyers, Pergamon Press, N. Y., 1966. 

Alkali metal arene radical anion complexes are useful sources of solvated electrons for reductive desulfonylation reactions.14 Aromatic compounds such... 

Site and stereocontrol of the reductive desulfonylation reactions of allylic and vinylic sulfones depend on the choice of the reducing agents and reaction conditions. With allylic sulfones migration of the double bond to the most stable position is usually observed with all the reagents investigated (Eq. 19).37 The migration of the double bond takes place with little or no stereocontrol, and different results can be obtained depending on the method employed as depicted in Eq. 20 for vinylic sulfones.38... 

Despite the great amount of interest in reductive desulfonylation reactions, very little research has addressed the stereospecific reductive desulfonylation of chiral a-substituted sulfones. Only limited success has been achieved as shown in Eq. 30.50 Lithium naphthalenide is used for the stereoselective SET desulfonylation of anomeric sulfones derived from 2-deoxy-D-glucose derivatives.51-54 The initial homolytic cleavage of the C-SO2 bond generates a cr-radical, which adopts an a-orientation due to stereoelectronic stabilization,55-57 forcing the anomeric substituent to adopt the (3-orientation, an arrangement that is retained through the reduction process (Eq. 31). 

By far, the most widely used method is the alkylation of an a-sulfonyl carbanion followed by reductive removal of the sulfonyl group. Different electrophiles such as alkyl halides, sulfonates, sulfinates, acetates, oxiranes, and electron-deficient multiple bonds are employed for the formation of the new C-C bond. Palladium-catalyzed it-allylic alkylation with a-sulfonyl carbanions is also a commonly used method. After the C-C bond formation, the conditions for the final desulfonylation reaction with the appropriate reagent will depend on the structure of the sulfone intermediate. 

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