Sodium Methylsulfinylmethylide: A Versatile Reagent

Introduction

Sodium methylsulfinylmethylide (sodium dimsylate, dimsylsodium), introduced by Corey and Chaykovsky, [1] has found widespread use [2] in organic synthesis because of its strong basic character, nucleophilicity and its use for the introduction of methylsulfinylmethyl group. It is ­conveniently prepared¹ by heating finely powered sodium hydride in an excess of anhydrous DMSO under nitrogen at about 70 °C until hydrogen evolution stops, resulting in a clear solution. Sodium amide can also be used as the base. [3]

The reagent is highly soluble in DMSO and such solutions are sensitive to heat and air, and decompose rapidly above 85 °C. [4] At 20 °C they lose 8% of their activity per week. Hence, it is probably best prepared when needed and used immediately. However, an ultrasound-mediated preparation⁴ has been reported for long-time storage of the reagent. Purity can be checked by titration with form­anilide using triphenylmethane as an indicator (colorless to deep red). [1]

References

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