Sodium amalgam desulfonylation with

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>. 

Some Compounds Reductively Desulfonylated with Sodium Amalgam... 

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... 

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. 

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. 

Allylamines Condensation of the A(,C-dianion of this reagent with carbonyl compounds leads to oxazin-2-ones. On treatment with sodium amalgam, the heterocycles undergo desulfonylative ring opening. 

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... 

---