Reduction of Alkylsulfonates

There is limited precedent for the reduction of alkyltosylates to alkanes using Sml2. It is likely that the mechanism of reduction involves in situ conversion of the alkyl tosylate to the alkyl iodide followed by reduction of the iodide.1 

In his early studies, Kagan showed that Sml2 can be used for the deoxygenation of epoxides.1 The deoxygenation of phosphine oxides and tin oxides is also effectively achieved using Sml2 provided that HMPA is used as an additive.59 

Representative procedure.61 To a stirred solution of t-BuOH (10 equiv) was added the sulfone 61 (1 equiv) and the solution was cooled to —78 °C. A solution of Sml2 in THF (5 equiv) was then added and the reaction mixture stirred for 10 min followed by the addition of HMPA (2.5 equiv). The reaction mixture was stirred at — 78 °C for 1 h, then at —45°C for 2h before warming to room temperature, diluting with H20 and extraction with EtOAc. The combined organic extracts were dried (MgS04) and the solvent was removed in vacuo. Crude product 62 was purified by column chromatography (EtOAc-benzene eluent). 

More recently, Marko has used Sml2 to reduce (5-benzoyloxy sulfones65 and sulfoxides66 in modified Julia Lythgoe olefinations. 

The accelerating effect of HMPA on the reduction of the S-O bond has allowed Sml2 to be used in excess for the deoxygenation of diaryl sulfones. Only moderate yields are obtained for the reduction of dialkyl sulfones.59 As discussed 

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