Mannich with sulfinic acids

Mannich-type condensation with sulfinic acids... 

Addition of sulfinate ions to the carbonyl group of aldehydes to form c-hydroxy sulfones (Bredereck et al., 1954, Bredereck and Bader, 1954) is also known, as is the participation of sulfinic acids as the acid component in Mannich-type condensation reactions with aldehydes (129) (Rawson and Engberts, 1970 Engberts and Strating, 1964, 1965). 

Substrates usefully employed in Mannich reactions are, in general, XH compounds having nucleophilic properties, with X being equal to C, N, or other heteroatoms (Fig. 4). In particular, CH compounds are suitably activated saturated and unsaturated derivatives, and NH substrates may be amines, amides, hetcrocyclcs, etc. Out of OH sub-stratcs, alcohols are mainly able to give stable Mannich products. Sulfur- and phosphorus-containing substrates are XH derivatives having the H atom bonded to the hetcroatom in the lower oxidation state, i.e., thiols, sulfinic acids, and, respectively, phosphine and phosphorous acid derivatives. As and Se compounds have also been successfully used. All these substrates are listed in more detail in Sec. D of this chapter. 

Aminosulfones (68) may be prepared by conjugate 1,4-addition of amines to a,p-unsaturated sulfones or by a Mannich-type reaction of a sulfinic acid with an aldehyde in the presence of an amine (Scheme 31). 

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