O-Mesitylenesulfonyl hydroxylamine

The powerful aminating agents hydroxylamine O-sulfonic acid and O-mesitylenesulfonyl-hydroxylamine have been used to prepare compounds (270)-(274) (80JCR(M)0514,76CPB2267). 

Boche and coworkers crystallized the lithium derivative of 3i, e.g. A-lithio N- t-butoxycarbonyl) O -(mesitylenesulfonyl)hydroxylamine . 

Recently, a direct kinetic study on the amination of substituted phenyhnagnesium bromides using Af,Af-dimethyl O-mesitylenesulfonyl hydroxylamine 3b as amination reagent has been reported by Erdik and Ate Ulkii . Rate data, the Hammett relationship and activation entropy support an Sn2 displacement of the carbon nucleophile on the electrophilic nitrogen. These results are consistent with the competition kinetics for electrophilic amination of substituted phenyl Grignard reagents with O-methylhydroxylamine In. ... 

Among the early attempts of amination of lithium and copper enolates were those which involved formation of a-A-(Boc)- or A-(Alloc)amino-substituted carboxylic esters, A-acyloxazolidinones and diethyl phosphonates (Scheme 33) ° . a-Lithum or a-copper derivatives of these enolates were aminated using A-lithium derivatives of A-Alloc O-(mesitylenesulfonyl)hydroxylamine 3j, NHBocOTos 31 and NHAllocOTos 3m. 

A series of eleven 1-aminopurinium mesitylene sulfonates were prepared in good yields by treatment of the corresponding purine with O-(mesitylenesulfonyl) hydroxylamine <85RTC302>. 

Symmetrical trialkylboranes can be converted to the corresponding primary amines28 by a variety of /V-hetcro-substituted amines chloramines1-2, hydroxylamine-O-sulfonic acid (HSA)1 3-29, O-mesitylenesulfonyl hydroxylamine (MSH)4, chloramine-T5, ammonium hy-droxide/sodium hypochlorite (in situ formed chloramine)6, and azidotrimethylsilane7. 

The results of this reaction sequence are summarized in Scheme 3. Reaction of phenyl isocyanates with methylaminoacetaldehyde dimethyl acetal gave the corresponding ureas (5) in 90-95% yields. The urea was then treated with sodium hydride, and after the reaction mixture had cooled to 5°C, the aminating reagent was added all at once. Of three aminating reagents-O-(mesitylenesulfonyl) hydroxylamine (2), 0-(2,4-dinitrophenyl)hydroxylamine (3.) and 0-(4-nitrophenyl)hydroxylamine (2), the latter was preferred as it is a stable, recrystallizable solid. The crude product from this reaction mixture consisted of the semicarbazide and the urea which are conveniently separated by flash chromatography (silica gel). 

For many years it was assumed that alkylation of quinazoline with methyl iodide gave only 3-methylquinazolinium iodide. More recently, however, with the aid of proton magnetic resonance, Bunting and Meathrel demonstrated that a mixture of 1-methyl- and 3-methylquinazolinium iodide were formed in the ratio 1 5 by this method.103 A phenyl substituent in position 4 directed methylation to N-l.104 Amination also was directed to N-l, as was shown by the reaction of O-mesitylenesulfonyl hydroxylamine with... 

The most commonly used hydroxylamine derivatives are hydroxylamine 0-sulfonic acid (HSA) (3) (or its alkali salts)5 and O-mesitylenesulfonyl-hydroxylamine (MSH) (4).6,7 Although HSA is more easily and cheaply prepared, it presents solubility problems (it is water-soluble but insoluble in most organic solvents except methanol and diglyme). In addition, it has rather weak aminating power and limited application the N-amination reaction fails with pyridines bearing electron-withdrawing substituents (e.g.,... 

O-Mesitylenesulfonyl)hydroxylamine (X) is used as a reagent for electrophilic NH2 transfer to the pyridine-like N of azoles and azines (cf p 273). The resulting N-aminated systems can be subjected to acylation, deprotonation (to give dipolar N-imides) and other transformations [76]. The following sequence of reactions may serve as an example ... 

N-Unsubstituted O-Sulfonylhydroxylamines. The acidic nature of hydroxy -lamine O-sulfonic acid makes it essentially useless in electrophilic animations of carbanions. One of the few exceptions is shown in Eq. 161. The explosive114115 0-(mesitylenesulfonyl)hydroxylamine animates alkylzirconium complexes (see Eqs. 41 and 51),116 acid dianions,115 and ester enolates.117 O-Arenesulfonylhy-droxylamines with no ortho substituents are thermally unstable at room temperature.11... 

Reaction of monocyclic 1,2,3-triazines 1 with mesitylenesulfonyl-O-hydroxylamine led to the isolation of 2-amino-l, 2,3-triazinium salts 5 which could be deprotonated by base to the 1,2,3-tri-azin-2-imines 6.246,247 The imino compounds could be acylated yielding either (acylimino)-1,2,3-triazines 6a or the dimers 7. 

Triazine 2-imines 18d-g are available from 4,6-disubstituted-l,2,3-triazines with 0-(mesitylenesulfonyl)hy-droxylamine (MSH) followed by treatment with potassium carbonate solution (Equation 19) <1988YZ1056>. N-2 Amination failed for monosubstituted 1,2,3-triazines 86a and 86b using both MSH and hydroxylamine-O-sulfonic acid (HOS). In the latter two cases, ring degradation by base occurred and only the 3-amino-2(3)-phenylacrylonitriles 98a and 98b were isolated as products, presumably via action of base on the intermediates 97. Lack of a substituent at C-6 of 86a and 86b was regarded as responsible for this failure <2004EJO4234> (Equation 20). 

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