[37477-17-1] · C10H13NO2 · O-Mesitoylhydroxylamine · (MW 179.24)
(reagent for electrophilic aminations, H2N transfers to nucleophiles)
Physical Data: oil; mp of N-acetyl-O-mesitoylhydroxylamine 128-129 °C.1
Preparative Method: a solution of 10.0 g (35.8 mmol) t-butyl N-mesitoyloxycarbamate in 150 mL of nitromethane was treated with a stream of anhydrous hydrogen chloride for 5-7 min. After standing for 15 min the precipitated solid (1) (mp 125-127 °C, dec) was filtered, washed with nitromethane, dried in air and then suspended in 100 mL of water and treated with 1 M sodium bicarbonate solution until gas evolution stopped. The resulting oil was extracted with three 15 mL portions of CH2Cl2, the extracts dried over magnesium sulfate, and the solvent removed from a water bath at room temperature under reduced pressure (ca. 12-20 mmHg). O-mesitoylhydroxylamine (2) remained as a clear, colorless oil; 5.5 g (86%) (eq 1).2
Handling, Storage, and Precautions: explosions which have been reported for compounds similar to (2), e.g. O-(Mesitylsulfonyl)hydroxylamine or O-(p-tolylsulfonyl)hydroxylamine,2 have not been described for (2).
While O-(mesitylsulfonyl)hydroxylamine is the reagent of choice for the N-amination of heteroaromatic and tertiary amines,1 it is (2) which should be used for the preparation of 1,1-disubstituted hydrazines from secondary amines (Table 1).1,2a,3 Compound (2) is also a good reagent for the amination of
anionic nitrogen atoms of amides, pyrroles, and related compounds, as shown in Table 2.4,5
One should mention here that O-(2,4-dinitrophenyl)hydroxylamine (8) also aminates substrates of this type quite well.1,6,7 In contrast, O-(mesitylsulfonyl)hydroxylamine1 is not a good reagent for such reactions.
O-Mesitoylhydroxylamine (2) was used (among others) for the a-amination of dilithiated carboxylic acids, RCHLiCO2Li;8 however, success was very poor. Other aminating reagents for these and other carbanions turned out to be much better, as excellently described in a recent review.9
Makhova et al. used (2) for the preparation of diaziridines,10 a reaction which is also performed with O-(mesitylsulfonyl)hydroxylamine.
Finally, (2) has been identified as an oxidative inhibitor of cysteine proteinases.11
Philipps-Universität Marburg, Germany