P-nitroacetates

Barton and Zard found that the base-catalyzed reaction of nitroalkenes or P-nitroacetates with alkyl isocyanoacetate or TosMIC gives pyrrole-2-carboxylates or 2-sulfonylpyrroles, respectively (see Eqs. 10.18 and 10.19).22 This reaction is very convenient for the synthesis of... 

A considerable number of acylarylamines, among them o-chloroacet-anilide, 2,6-dichloro-4-nitroacetanilide, and l-acetamido-2-methylan-thraquinone, form abnormal nitroso compounds with nitrous fumes others, such as 4-dimethylamino-4 -acetamidoazobenzene, benzene-p-toluidide, and diacetyl-1,3-phenylene diamine, do not yield nitroso compounds with nitrous fumes a third group, which includes p-nitroacet-anilide and a- and /3-acetamidoanthraquinone, is recovered unchanged after the same treatment.63 In general, the acetamido group submits to nitrosation, whereas the benzoyl and benzenesulfonyl and toluenesul-fonyl derivatives of amines are resistant to the notion of nitrous fumes. 

This series of compounds was also discussed briefly by Quilico in 1962 and only a limited number of new representatives have been reported 62HC(17)l,p. 3). The pressure reaction of ethylene and nitric acid in the presence of Ni, Zn or Cu produced 3,3 -bis(isoxazoline) 70FRP94493), and the isoxazoline IV-oxide (515) was prepared by the reaction of /3-dimethylaminoacrylaldehyde and methyl nitroacetate (74IZV845). 

The reaction mixture is cooled to —15° 3° and 116 g. (1.16 moles) of concentrated sulfuric acid is added with vigorous stirring over approximately 1 hour at such a rate that the reaction temperature is maintained at —15°. The reaction mixture is allowed to warm to room temperature over a 4-hour period and to stir for another 4 hours at room temperature. The precipitate is removed by suction filtration and the filtrate is concentrated on a rotary evaporator under reduced pressure at 30-40°. The residual oil is dissolved in benzene and washed with water, The benzene layer is dried over anhydrous sodium sulfate and the benzene is removed by distillation. Further distillation under reduced pressure yields 30-32 g. (66-70%) of methyl nitroacetate, b.p. 80-82° (8 mm.). 111-113° (25 mm.) (Note 5). 

P. Borrachero, M. J. Dianez, M. D. Estrada, M. Gomez-Guillen, A. Gomez-Sanchez, A. Lopez-Castro, and S. Perez-Garrido, Silica gel-catalysed addition of methyl nitroacetate to 1, 2 3, 4-di-O-isopropylidene-a-D-ga/acto-hexodialdo-... 

The first application of microwave irradiation in conjunction with dry media in the generation of nitrile oxide intermediates was reported by Hamelin [29]. In this example, methyl nitroacetate (170) was mixed with a dipolarophile in the presence of catalytic amounts of toluene-p-sulfonic acid (PTSA) (10% weight). Subsequent microwave irradiation led to the formation of the corresponding heterocyclic adducts (Scheme 9.52). Reactions were performed in an open vessel from which water was continuously removed [103], Likewise, irradiation in a domestic oven of a mixture of ethyl chloro(hydroxyimino)acetate (173) and a dipolarophile over alumina led to the same results in only a few minutes (Scheme 9.52) [103]. 

Field effects. These were discussed on p. 17. As an example of the influence of field effects on acidity, we may compare the acidity of acetic acid and nitroacetic acid ... 

Dipotassium Nitroacetate (DKNA). See under Acetic Acid in Vol 1, p A27-R... 

Fig. 4. Bronsted plot of the dependence of the rate of proton transfer (log10 feg) from ethyl nitroacetate to bases (B) upon ApA, the difference in pA between the carbon acid and the base. Both feg and ApA are statistically corrected and negative ApA corresponds to thermodynamically favourable proton transfer from the carbon acid. The bases studied are water 1 carboxylate ions 2—7 pyridines 8—11 phenoxide ions 12, 13. Redrawn with permission from D. J. Barnes and R. P. Bell, Proc. R. Soc. A, 318 (1970) 421.

Ethyl nitroacetate-Dicthyl azodicarboxyl-ate-Triphcnylphosphine, 182 Ethyl 2-phenylsulfinyIacetate, 183 Ethyl vinyl ether, 184 d-Ethynyl-0-propiolactone, 283 Ethynyl p-tolyl sulfone, 183 Ethynyltrimethylsilane, 177 Evodone, 231,232,279 Exaltone, 35... 

Reactions of carbonyl compounds with nitroalkanes like nitromethane (Henry reaction) are described in Volume 2, Chapter 1.10. The doubly activated ethyl nitroacetate readily reacts with aliphatic, aromatic and heteroaromatic aldehydes to give a,p-unsaturated-a-nitrocarboxylic acid esters in the presence of TiCU/V-methylmorpholine as mixtures of cis and trans isomers. ... 

V, N -Dicyclohexylcarbodiimide. DCC Nitroacetic esters. Esterification conventional methods, but it can be p serves to anchor nitroacetyl groups to h> 4-O-Alkyltetronic acids.- Preparau acids under mild conditions relies on the e... 

In the second example, Hamelin et al. [47] reported the first microwave-assisted solvent-free catalyzed conditions for generation of nitrile oxide intermediates 17. In this work, a mixture of methyl nitroacetate 16 (as 1,3-dipole precursor), dimethyl acetylene dicarboxylate (DMAD) 18 (as dipolarophile), and p-toluene sulfonic acid (PTSA) as catalyst (10% w/w) was irradiated neat for 30 min. The reaction was performed in an open vessel from which water was continuously removed [48]. In this manner, the desired isoxazole adduct 19 was obtained in excellent yield (91%). 

The anions of malonate esters, cyclopentadiene, p-keto esters, ketones, aldehydes, a-nitroacetate esters, Meldrum s acid, diethylaminophosphonate Schiff bases, p-diketones, /3-sulfonyl ketones and esters, andpolyketides represent the wide variety of carbon nucleophiles effective in this reaction. Generation of the stabilized anions normally is... 

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