Reductive desulfonylation, with sodium amalgam

Some Compounds Reductively Desulfonylated with Sodium Amalgam... 

Use of Sodium Amalgam. Reductive desulfonylation with metal amalgams, and particularly Na/Hg (5-6%), is the most widely employed and general method for all types of sulfones even though it requires the handling of substantial quantities of mercury, which is toxic and relatively expensive. 

Desulfonylation of a-sulfonylacetates. Desulfonylation of these substrates is not satisfactory by the usual methods (Zn-HOAc, Raney Ni-C,H5OH, sodium amalgam), but can be conducted in 70-75% yield with sodium-ethanol in THF (modified Bouveault-Blanc reduction). The substrates (2) are obtained by Wolff rearrangement of a-acyl-a-benzyl-sulfonyldiazomethanes (1).1... 

The reductive desulfonylation of vinylic sulfones has been mainly carried out with sodium and aluminum amalgams, Sml2, and Mg in M,Al-dimethyl-formamide (DMF) in the presence of chlorotrimethylsilane (TMSC1). The configuration of the double bond is not necessarily preserved in the desulfonylation of vinylic sulfones when Na/Hg is employed. This reagent is the most widely used when there is no need for stereochemical control as shown in Eqs. 2139 and 22.40... 

Alternatively, reductive desulfonylation of the desilylated cycloadduct with 6% sodium amalgam in buffered methanol afforded a 2 1 mixture of isomers. The products are formally the result of TMM Pd addition to 2-cyclohexenone (poor yielding) followed by ketone reduction58. 

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