[16182-15-3] · C9H14N2O2S · Mesitylenesulfonylhydrazide · (MW 214.32)
(used to form diazene;1 condenses with ketones and aldehydes to form hydrazones that can be used as a source of reactive intermediates such as diazoalkanes, carbenes, carbenium ions, and alkyllithiums;7,8 a good reagent for the Eschenmoser fragmentation4)
Alternate Names: MSH; 2,4,6-trimethylbenzenesulfonylhydrazide.
Physical Data: mp 105 °C (dec).
Solubility: sol ether, THF, benzene, dichloromethane, chloroform, ethanol; insol water, hydrocarbons.
Form Supplied in: solid; widely available.
Analysis of Reagent Purity: IR, NMR.
Handling, Storage, and Precautions: is stable for many months below 0 °C and should be stored in a freezer. It is a toxic, potentially flammable solid which should be handled with gloves in a fume hood under an inert atmosphere.
Mesitylenesulfonylhydrazide in refluxing methanol is a convenient source of diazene (diimide). It has intermediate reactivity, decomposing 16 times faster than p-Toluenesulfonylhydrazide (tosylhydrazide) and 24 times slower than 2,4,6-Triisopropylbenzenesulfonylhydrazide (trisylhydrazide) under base-catalyzed conditions.1 An analogous use of MSH is in allylic diazene rearrangements.2 Eq 1 illustrates a recent example whereby an allylic alcohol is ionized with a Lewis acid and the resulting allyl cation trapped with MSH to give the diazene, which stereospecifically yields the rearranged product.3
MSH condenses with ketones to form hydrazones, which participate in the Eschenmoser fragmentation. Eq 2 shows the mild fragmentation of two epoxy ketones to form 1-cyclononyn-4-one and 1-cyclodecyn-4-one in 1:1 CH2Cl2-AcOH at rt; compounds not accessible using the less reactive p-toluenesulfonylhydrazide.4
MSH is oxidized by Benzeneseleninic Acid to give selenosulfonates in excellent yield and which themselves have diverse synthetic utility.5,6 The few examples that employ mesitylenesulfonylhydrazones in the aprotic Bamford-Stevens reaction show that triisopropylbenzenesulfonylhydrazones are superior.7,8 Hydrazones of esters (hydrazimidates) have been prepared using MSH but their properties have not been investigated.9
A. Richard Chamberlin & James E. Sheppeck II
University of California, Irvine, CA, USA