Sodium methylsulfinylmethylide

Sodium methylsulfinylmethylide (also called NaDMSO) is the conjugate base of dimethyl sulfoxide. It has several uses in organic chemistry as a base and nucleophile.

Since the first publication in 1965 by Corey et al.^[1], a large number of publications have described additional uses for this reagent.^[2]

Additional recommended knowledge

Essential Laboratory Skills Guide

Daily Sensitivity Test

What is the Correct Way to Check Repeatability in Balances?

Preparation

Sodium methylsulfinylmethylide is prepared by heating sodium hydride or sodium amide^[3] in DMSO at 70 °C for 1 hr.

Applications

As a Base

The pKa of DMSO is 35, which leads NaDMSO to be a powerful Brønsted base. NaDMSO is used in the generation of phosphorus and sulfur ylides.^[4] NaDMSO in DMSO is especially convenient in the generation of dimethyloxosulfonium methylide and dimethylsulfonium methylide.^[1][5]

As a Nucleophile

Reaction with esters

NaDMSO will condense with esters (1) to form β-ketosulfoxides (2), which have been shown to be very useful synthetic intermediates.^[6] Reduction of β-ketosulfoxides with aluminium amalgam gives methyl ketones (3).^[7] Reaction with alkyl halides followed by elimination gives α,β-unsaturated ketones (4). Interestingly, β-ketosulfoxides can also be used in the Pummerer rearrangement to introduce nucleophiles alpha to a carbonyl (5).^[8]

References