I am rereading Nigel S. Simpkins' 1993 book Sulphones in Organic Synthesis
. There are at least two sections that deal with sodium sulfinates as nucleophiles to make sulfones. One section (starting on p. 11) discusses the S vs. O alkylation issue (the other section is on p. 60). This section mentioned that replacing methanol with polyethylene glycol as the solvent was advantageous. It also indicated that the product of O-alkylation, a sulfinate ester, could sometimes rearrange to make the sulfone. Another work-around is to run the reaction under conditions where the sulfinate ester hydrolyzes back to starting material. Eventually the sulfone is produced. The use of an ion-exchange resin to make the counter-ion a quaternary ammonium salt is also discussed. This section also discussed ultrasound as a method to speed up the reaction. In addition to an alkyl halide and TolSO2
Na, one paper used DBU and acetonitrile. I am not sure what the DBU is doing, but I will try to obtain this paper and see (possibly the authors started with a sulfinic acid, as opposed to a sodium salt).
"A Simple Synthesis of Sulfones" Biswas G and Mal D, J. Chem. Res. (S) 1988 308.
The discussion that I am having the most trouble understanding concerns hard vs. soft electrophiles. The reaction of TolSO2
Na with dimethyl sulfate gave almost entirely the sulfinate ester, but the use of methyl iodide gave predominantly the sulfone. It is surprising to me that the leaving group makes such a big difference, but the authors of the 1968 paper invoke hard and soft acid-base theory to explain it. It makes me think that there may be a difference between ICH2P(O)(OEt)2
and the corresponding tosylate in the reaction I am planning.
Meek JS and Fowler JS, J. Org. Chem. 1968 33 3422. https://pubs.acs.org/doi/pdf/10.1021/jo01273a014
Kielbasinski R...Mikolajczyk M. Tetrahedron 1988 44 6687-6692.