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Solvent‐Free Nucleophilic Addition ofN‐Alkylhydroxylamines to SubstitutedNitroolefins: Formation of Nitrones by aTandem processChinnadurai Amutha a & Shanmugam Muthusubramanian aa Department of Organic Chemistry, Madurai Kamaraj University, Madurai,IndiaPublished online: 28 Jan 2008.

To cite this article: Chinnadurai Amutha & Shanmugam Muthusubramanian (2008) Solvent‐Free NucleophilicAddition of N‐Alkylhydroxylamines to Substituted Nitroolefins: Formation of Nitrones by a Tandem process,Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,38:3, 328-337, DOI: 10.1080/00397910701767031

To link to this article: http://dx.doi.org/10.1080/00397910701767031

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Solvent-Free Nucleophilic Additionof N-Alkylhydroxylamines to Substituted

Nitroolefins: Formation of Nitronesby a Tandem process

Chinnadurai Amutha and Shanmugam Muthusubramanian

Department of Organic Chemistry, Madurai Kamaraj University,

Madurai, India

Abstract: Nucleophilic addition of 1-methyl-2-arylethylhydroxylamine to substituted

b-nitrostyrene under solvent-free conditions has led to unexpected nitrones via a

tandem process involving 1,4-addition and elimination.

Keywords: a-aryl-N-[1-methyl-2-arylethyl]nitrone, 1-methyl-2-arylethyl hydroxyla-

mine, nucleophilic addition, solvent-free reaction, tandem process

Nitroalkenes undergo addition reactions with oxygen and sulfur-centered

nucleophiles.[1,2] Nucleophilic addition of aromatic amines[3] and hydrazino

bases[4] to nitrostyrenes have also been reported. Hydroxylamines have

proved their versatility as reaction intermediates in the construction of

organic frameworks. N,O-Disubstituted hydroxylamines are important inter-

mediates in the synthesis of natural products.[5] Diaziridines are formed when

O-substituted hydroxylamines interact with aldimines and primary aliphatic

amines.[6] Hydroxylamines are also biologically important, and the mutagenic

activity of several N-hydroxylamines toward strains of Escherichia coli and Sal-

monella typhimurium has been reported.[7] Arylhydroxylamines act as

Received in India July 13, 2007

Address correspondence to Shanmugam Muthusubramanian, Department of

Organic Chemistry, Madurai Kamaraj University, Madurai 625 021, India. E-mail:

muthumanian2001@yahoo.com

Synthetic Communicationsw, 38: 328–337, 2008

Copyright # Taylor & Francis Group, LLC

ISSN 0039-7911 print/1532-2432 online

DOI: 10.1080/00397910701767031

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carcinogens.[8] In view of all this, we planned to effect nucleophilic addition of

N-alkylhydroxylamine to nitrostyrene to get N,N-diakylhydroxylamine because

the target compounds may exhibit enhanced biological activity.

We planned to investigate the nucleophilic properties of 1-methyl-2-ary-

lethylhydroxylamine 1 with different substrates under solvent-free conditions.

The hydroxylamine under discussion was prepared by the controlled careful

reduction[9] of b-methyl-b-nitrostyrene.[10] Nitroalkenes are also potential

substrates for nucleophilic attack in a 1,4-fashion addition. Thus, we

planned to effect nucleophilic addition of hydroxylamines 1 on substituted

nitrostyrenes 2 in the expectation of getting secondary hydroxylamines. The

resultant secondary hydroxylamines can be further functionalized or can be

used to generate new C-N bonds and hence can act as good precursors for

further synthetic transformations. In addition, they may be biologically

more active than the starting nitrostyrene because of the additional nitrogen.

In the present investigation, an equimolar mixture of the hydroxylamine 1

and nitrostyrene 2 was ground well and kept at room temperature (308C). The

mixture soon became a pasty mass sticking to the wall of the mortar. As the

reaction progressed, crystals came out of the mass and completely got thrown

out in 2 days. The mixture was then treated with petroleum ether (40–608C),

and the solid mass obtained was filtered. The product ultimately was found to

be a single entity, 3, with 80–85% conversion (Scheme 1). The petroleum

ether solution contained another unstable compound, 4, in a relatively poor

yield (less than 15%), undergoing decomposition to 3 in solution. The 1H

NMR spectrum of compound 3 gives a doublet around 1.5 ppm, and two

doublets of doublets around 2.8 ppm and 3.3 ppm. All the compounds

exhibited a multiplet around 4.1 ppm apart from signals due to two aromatic

nuclei. There was also a downfield singlet appearing around 7.1 ppm. The 13C

NMR spectra of all the compounds showed signals around 19, 25, 30, and

73 ppm apart from the aromatic carbons. There was no nitro group in these

compounds as evidenced by the infrared spectra, and signals due to nitroethyl

group were absent in the NMR data. A close investigation of the structure of

these compounds based on one- and two-dimensional NMR suggests that the

compound 3 is a nitrone, a-aryl-N-[1-methyl-2-arylethyl] nitrone, which can

be easily obtained from arylaldehyde and the hydroxylamine 1.

Authentic samples of nitrones 3 were prepared from the corresponding

arylaldehydehyde and hydroxylamine 1 and were compared with the

product obtained in the previous reaction by mixed melting point and the fin-

gerprint region of their IR spectra. Thus, the compounds 3 isolated in the

present investigation are none other than the nitrones. To explore the

veracity of this nucleophilic attack, different alkyl-substituted hydroxylamines

were subjected to reaction with differently substituted b-methyl-b-nitrostyr-

enes, and in all the cases, reaction took place excellently. Incidently, all the

nitrones, except 3a, obtained by this method are hitherto unknown. The

yield, melting point, 1H NMR, and 13C NMR data of all the nitrones are

presented in Table 1.

Formation of Nitrones by a Tandem Process 329

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The outcome is surprising, as a secondary hydroxylamine has been

expected with a possible dehydration, giving an imine 5 or 6 (Scheme 2),

which may undergo further hydrolysis. The formation of the nitrone in the

nucleophilic attack of the hydroxylamine on nitroolefin can be explained by

a tandem addition–elimination sequence. The leaving ability of CH3C̄HNO2

can be understood because the nitro group is a powerful electron-withdrawing

group, thereby stabilizing the anion to a great extent. Thus nitroethane has been

eliminated from the initially formed secondary hydroxylamine by the

mechanism shown in the following scheme (Scheme 3). It should be

mentioned that such an elimination involving nitroalkane has already been

noticed in some nucleophilic attack involving amine as the nucleophile.[11]

To prove that the reaction goes via the addition–elimination mechanism,

the reaction was deliberately stopped at an intermediate stage after 3 h, and

from the 1H NMR spectrum of the crude reaction mixture, it was found to

contain more hydroxylamine 4 and relatively poor yield of the nitrone 3.

The mass spectrum of 3a, N-(1-methyl-2-phenylethyl)-C-phenylnitrone

exhibits the molecular ion peak at 239 with relative abundance of 30%. The

base peak corresponds to m/e of 117, indicating the formation ofb-methylstyrene.

This is expected as the nitrone functionality gets eliminated with the abstraction of

Scheme 1. a) Ar ¼ phenyl, X ¼ H; b) Ar ¼ phenyl, X ¼ Cl; c) Ar ¼ phenyl,

X ¼ OH; d) Ar ¼ phenyl, X ¼ Me; e) Ar ¼ 4-chlorophenyl, X ¼ H; f) Ar ¼ 4-chlor-

ophenyl, X ¼ OMe; g) Ar ¼ 3,4-methylenedioxyphenyl X ¼ H; h) Ar ¼ 2-thienyl,

X ¼ H; i) Ar ¼ 2-thienyl, X ¼ Cl; j) Ar ¼ 3,4-dimethoxy, X ¼ H; k) Ar ¼ 2,4-

dichloro, X ¼ H; l) Ar ¼ 4-methoxyphenyl, X ¼ H; m) Ar ¼ 4-methoxyphenyl,

X ¼ Cl; n) Ar ¼ 4-methoxyphenyl, X ¼ NO2; o) Ar ¼ 4-methoxyphenyl, X ¼ Me;

p) Ar ¼ 4-methoxyphenyl, X ¼ OH; q) Ar ¼ 4-methoxyphenyl, X ¼ OMe; r)

Ar ¼ 4-methylphenyl, X ¼ H; s) Ar ¼ 4-nitrophenyl, X ¼ H; t) Ar ¼ 2-cholorphenyl,

X ¼ H; u) Ar ¼ phenyl, X ¼ NO2.

C. Amutha and S. Muthusubramanian330

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Table 1. Yield, melting point, and NMR spectral data of 3a–3u

Sl. no. Compd. Mp (8C)

Yield

(%) 1H NMR (d scale) 13C NMR (d scale)

1 3a 101 80 1.55, d (J ¼ 6.3 Hz), 3H; 4.09, m, 1H; 2.82, dd (J ¼ 13.5,

4.5 Hz), 1H; 3.34, dd (J ¼ 13.5, 9.3 Hz), 1 H; 7.12, s, 1H;

6.80–7.30, m, 8H; 8.15, d (J ¼ 8 Hz), 2H

19.0, 39.6, 73.2, 128.4, 128.5,

128.6, 129.9, 130.2, 130.3,

132.5, 133.8, 136.1

2 3b 150 95 1.55, d (J ¼ 6.3 Hz), 3H; 4.09, m, 1H; 2.89, dd (J ¼ 13.5,

5.1 Hz), 1H; 3.33, dd (J ¼ 13.5, 8.7 Hz), 1H; 7.05, s, 1H;

7.20–7.40, m, 7H; 8.1, d (J ¼ 9.3 Hz), 2H

19.3, 41.0, 74.5, 127.2, 128.9,

129.0, 129.1, 129.3, 130.2,

132.9, 135.9, 138.0

3 3c 133 87 1.53, d (J ¼ 6.3 Hz), 3H; 4.08, m, 1H; 2.89, dd (J ¼ 13.8,

5.4 Hz), 1H; 3.32, dd (J ¼ 13.8, 8.4 Hz), 1H; 7.01, s, 1H;

6.93, d (J ¼ 8.7 Hz), 2H; 7.20, s, 5H; 8.00, d, (J ¼ 8.7 Hz),

2H

19.0, 40.8, 73.5, 116.4, 121.1,

127.2, 128.9, 129.4, 132.3,

137.2, 137.8, 161.0

4 3d Viscous

liquid

85 1.54, d (J ¼ 6.3 Hz), 3H; 4.10, m, 1H; 2.87, dd (J ¼ 13.5,

5.4 Hz), 1H; 3.33, dd (J ¼ 13.5, 9.0 Hz), 1H; 2.30, s, 3H;

7.05, s, 1H; 7.17–7.25, m, 7H; 8.05, d (J ¼ 8.4 Hz), 2H

19.4, 41.0, 74.1, 22.0, 127.1,

128.1, 128.9, 129.0, 129.3,

129.5, 133.9, 138.3, 140.9

5 3e 105 85 1.55, d (J ¼ 6.3 Hz), 3H; 4.08, m, 1H; 2.81, dd (J ¼ 13.8,

4.8 Hz), 1H; 3.35, dd (J ¼ 13.8, 9.3 Hz), 1H; 7.08, s, 1H;

7.12–7.37, m, 7H; 8.15, m, 2H

19.1, 39.7, 73.7, 128.3, 128.5,

128.5, 130.1, 130.2, 132.5,

133.4, 136.2 (one carbon

merges with another)

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Table 1. Continued

Sl. no. Compd. Mp (8C)

Yield

(%) 1H NMR (d scale) 13C NMR (d scale)

6 3f 110 86 1.45, d (J ¼ 6.3 Hz), 3H; 3.99, m, 1H; 2.72, dd (J ¼ 13.5,

5.1 Hz), 1H; 3.18, dd (J ¼ 13.5, 8.7 Hz), 1H; 6.96, s, 1H;

6.60, dd (J ¼ 6.9, 1.8 Hz), 2H; 6.90, dd, (J ¼ 8.4, 1.8 Hz),

2H; 7.20, dd, (J ¼ 6.90, 1.80 Hz), 2H; 8.00, dd (J ¼ 7.20,

1.80 Hz), 2H; 3.64, s, 3H

19.3, 40.1, 74.7, 55.5, 112.0,

114.2, 129.0, 129.2, 130.1,

130.3, 132.7, 135.8, 158.8

7 3g 140 90 1.52, d (J ¼ 6.3 Hz), 3H; 4.07, m, 1H; 2.77, dd (J ¼ 13.8,

5.1 Hz), 1H; 3.27, dd (J ¼ 13.8, 9.0 Hz), 1H; 7.10, s, 1H;

8.05, d (J ¼ 8.4 Hz), 2H; 5.84, d (J ¼ 1.5 Hz); 5.86, d,

(J ¼ 1.5 Hz); 6.60–6.70, m, 3H; 7.30–7.40, m, 3H

18.0, 40.2, 74.0, 100.8, 108.2,

109.2, 122.0, 128.3, 128.5,

130.1, 130.4, 131.5, 133.3,

146.2, 147.6

8 3h 123 93 1.59, d (J ¼ 6.3 Hz), 3H; 4.19, m, 1H; 3.13, dd (J ¼ 15.0,

4.8 Hz), 1H; 3.61, dd (J ¼ 15.0, 9.0 Hz), 1H; 7.22, s, 1H;

6.80-6.90, m, 2H; 7.41-7.46, m, 3H; 7.13, dd (J ¼ 5.1,

2.4 Hz), 1H; 8.18–8.22, m, 2H

20.3, 35.9, 75.3, 125.7, 127.8,

128.4, 129.8, 130.1, 131.7,

131.8, 135.1, 140.9

9 3i 110 90 1.57, d (J ¼ 6.6 Hz), 3H; 4.10, m, 1H; 3.10, dd (J ¼ 15. 0,

4.8 Hz), 1H; 3.57, dd (J ¼ 15.0, 9.0 Hz), 1H; 7.16, s, 1H;

7.35, d (J ¼ 8.7 Hz), 2H; 8.14, d (J ¼ 8.7 Hz), 2H; 7.13, dd

(J ¼ 5.1, 1.2 Hz), 1H; 6.86, dd (J ¼ 3.6, 5.1 Hz), 1H; 6.82,

dd (J ¼ 3.6, 1.2 Hz), 1H

18.8, 34.5, 74.0, 124.3, 126.3,

127.0, 128.7, 128.8, 129.8,

132.6, 135.6, 139.2

10 3j 140 93 1.55, d (J ¼ 6.3 Hz), 3H; 4.06, m, 1H; 2.76, dd (J ¼ 13.5,

4.2 Hz), 1H; 3.31, dd (J ¼ 13.5, 9.6 Hz), 1H; 7.05, s, 1H;

3.60, s, 3H; 3.79, s, 3H; 7.34–7.37, m, 3H; 8.13–8.18, m,

2H; 6.68–6.72, m, 3H

19.0, 40.0, 74.2, 55.5, 55.7,

111.0, 111.9, 120.8, 128.3,

128.5, 130.2, 130.3, 130.4,

133.6, 147.7, 148.7

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11 3k 85 87 1.57, d (J ¼ 6.3 Hz), 3H; 4.26, m, 1H; 3.08, dd (J ¼ 13.5,

4.5 Hz), 1H; 3.36, dd (J ¼ 13.5, 9.3 Hz), 1H; 7.09, s, 1H;

7.03, dd (J ¼ 8.4, 2.1 Hz), 1H; 7.18, d (J ¼ 8.4 Hz), 1H;

7.38, m, 4H; 8.13, m, 2H

19.0, 37.5, 71.6, 127.2, 128.4,

128.5, 129.1, 129.7, 130.1,

130.3, 132.5, 133.4, 133.9,

134.3

12 3l 60 85 1.53, d (J ¼ 6.3 Hz), 3H; 4.26, m, 1H; 2.81, dd (J ¼ 13.5,

4.8 Hz), 1H; 3.29, dd (J ¼ 13.5, 9.0 Hz), 1H; 7.08, s, 1H;

6.75, d (J ¼ 8.7 Hz), 2H; 7.10, d, (J ¼ 8.7 Hz), 2H; 8.10, m,

2H; 7.36, m, 3H; 3.71, s, 3H

18.9, 39.7, 74.1, 55.1, 113.8,

128.3, 128.5, 129.8, 129.9,

130.0, 130.4, 133.3, 158.3

13 3m 110 88 1.53, d (J ¼ 6.3 Hz), 3H; 4.07, m, 1H; 2.80, dd (J ¼ 13.8,

5.1 Hz), 1H; 3.26, dd (J ¼ 13.8, 9.0 Hz), 1H; 7.04, s, 1H;

3.72, s, 3H; 6.75, d (J ¼ 8.7 Hz), 2H; 7.07, d (J ¼ 8.7 Hz),

2H; 7.33, d (J ¼ 8.7 Hz), 2H; 8.10, d (J ¼ 8.7 Hz), 2H

19.3, 40.1, 74.7, 55.5, 114.2,

129.0, 129.2, 130.1, 130.3,

132.7, 135.8, 158.8 (One

carbon merges with another)

14 3n 90 85 1.56, d (J ¼ 6.3 Hz), 3H; 4.18, m, 1H; 2.84, dd (J ¼ 13.8,

4.5 Hz), 1H; 3.25, dd (J ¼ 13.8, 9.3 Hz), 1H; 7.07, s, 1H;

3.70, s, 3H; 6.75, d (J ¼ 8.4 Hz), 2H; 7.07, d (J ¼ 8.4 Hz),

2H; 8.20, d (J ¼ 8.7 Hz), 2H; 8.29, d (J ¼ 8.7 Hz), 2H

19.3, 40.3, 75.6, 55.5, 114.3,

124.0, 129.1, 129.7, 130.2,

131.9, 136.4, 147.9, 158.8

15 3o 108 89 1.52, d (J ¼ 6.3 Hz), 3H; 4.05, m, 1H; 2.80, dd (J ¼ 13.5,

5.1 Hz), 1H; 3.29, dd (J ¼ 13.5, 8.7 Hz), 1H; 7.04, s, 1H;

2.35, s, 3H; 3.72, s, 3H; 6.75, d (J ¼ 8.7 Hz), 2H; 7.09, d

(J ¼ 8.7 Hz), 2H; 7.18, d (J ¼ 8.1 Hz), 2H; 8.06, d

(J ¼ 8.1 Hz), 2H

19.3, 40.1, 74.3, 22.0, 55.5,

114.2, 128.1, 129.0, 129.4,

130.1, 130.3, 133.8, 140.9,

158.7

16 3p 138 87 1.52, d (J ¼ 5.7 Hz), 3H; 4.04, m, 1H; 2.83, dd (J ¼ 13. 2,

4.8 Hz), 1H; 3.28, dd (J ¼ 13.2, 8.7 Hz), 1H; 7.01, s, 1H;

3.71, s, 3H; 6.75, d (J ¼ 7.8 Hz), 2H; 6.93, d (J ¼ 8.1 Hz),

2H; 7.08, d (J ¼ 7.8 Hz), 2H; 8.06, d (J ¼ 8.1 Hz), 2H

18.9, 39.9, 73.7, 55.6, 114.3,

116.3, 121.2, 129.9, 130.4,

132.3, 137.0, 158.7, 160.9

(continued )

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Table 1. Continued

Sl. no. Compd. Mp (8C)

Yield

(%) 1H NMR (d scale) 13C NMR (d scale)

17 3q 92 89 1.52, d (J ¼ 6.6 Hz), 3H; 4.03, m, 1H; 2.80, dd (J ¼ 13.8,

4.8 Hz), 1H; 3.29, dd (J ¼ 13.8, 8.7 Hz), 1H; 7.01, s, 1H;

3.72, s, 3H; 3.82, s, 3H; 6.75, d (J ¼ 8.4 Hz), 2H; 6.89, d

(J ¼ 9.0 Hz), 2H; 7.09, d (J ¼ 8.4 Hz), 2H; 8.16, d

(J ¼ 9.0 Hz), 2H

19.3, 40.0, 74.0, 55.5, 55.7,

114.1, 114.2, 123.8, 130.3,

130.4, 130.9, 133.4, 158.7,

161.2

18 3r 105 82 1.52, d (J ¼ 6.6 Hz), 3H; 4.03, m, 1H; 2.78, dd (J ¼ 13. 8,

4.8 Hz), 1H; 3.30, dd (J ¼ 13.8, 8.7 Hz), 1H; 7.03, s, 1H;

2.30, s, 3H; 7.25, m, 7H; 8.14, d (J ¼ 9.0 Hz), 2H

18.5, 40.3, 73.8, 21.6, 127.1,

128.1, 128.9, 129.1, 129.3,

129.7, 133.9, 138.6, 140.3

19 3s 140 85 1.52, d (J ¼ 6.3 Hz), 3H; 4.02, m, 1H; 2.80, dd (J ¼ 13.8,

4.8 Hz), 1H; 3.29, dd (J ¼ 13.8, 8.7 Hz), 1H; 7.01, s, 1H;

8.12, d (J ¼ 9.0 Hz), 2H; 8.00, d (J ¼ 9.3 Hz), 2H; 7.35, m,

5H

18.7, 39.7, 73.6, 124.2, 128.6,

129.1, 129.4, 130.1, 130.3,

133.9, 137.2, 140.9

20 3t 115 80 1.54, d (J ¼ 6.6 Hz), 3H; 4.02, m, 1H; 2.80, dd (J ¼ 13.8,

4.8 Hz), 1H; 3.32, dd (J ¼ 13.8, 8.7 Hz), 1H; 7.01, s, 1H;

8.12, d, (J ¼ 9.0 Hz), 2H; 7.55, m, 7H

19.1, 39.7, 74.0, 127.2, 128.4,

128.5, 128.9, 129.1, 129.2,

130.0, 130.9, 132.5, 133.9,

134.3

21 3u 110 74 1.52, d (J ¼ 6.6 Hz), 3H; 4.03, m, 1H; 2.78, dd (J ¼ 13.8,

4.8 Hz), 1H; 3.30, dd (J ¼ 13.8, 8.7 Hz), 1H; 7.03, s, 1H;

8.14, d (J ¼ 9.0 Hz), 2H; 8.20, d (J ¼ 9.3 Hz), 2H; 7.35, m,

5H

19.3. 39.4, 74.2, 124.6, 126.1,

128.0, 128.4, 130.3, 130.3,

133.8, 133.9,140.4

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b-hydrogen, giving the stable benzaldoxime as indicated in the fragmentation

scheme. The expected (M-16) peak, a salient feature in a,N-diaryl nitrones, is

totally absent in this system, indicating that the fragmentation dominates the

other popular fragmentations of nitrones. The benzyl radical cation also appears

dominant, with 70% relative abundance (Scheme 4). The molecular ion peak

has a poor intensity, less than 10% relative abundance, in most of the cases.

This one-pot conversion of nitrostyrene and hydroxylamine to nitrone is a

new route for the synthesis of nitrones, though the nitrone can be easily

prepared from the respective aldehydes. The same product with almost the

same yield has been obtained when the substrates were refluxed in ethanol

for 3 h. In conclusion, the nucleophilicity of the hydroxylamines has been

Scheme 3.

Scheme 2.

Formation of Nitrones by a Tandem Process 335

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found to be very effective under solventless conditions, though the expected

hydroxylamines undergo subsequent elimination.

EXPERIMENTAL

Melting points are uncorrected. NMR spectra were recorded on a Bruker 300-

MHz/75-MHz instrument in CDCl3 using TMS as internal standard.

Chemical shifts are given in parts per million (d scale), and coupling

constants are given in hertz. Mass spectra were recorded on a Finnigan GC-

MS instrument. The substituted nitrostyrenes and other a,b-unsaturated

nitro compounds have been prepared by the condensation of the corresponding

aldehydes with nitroethane.[10] The partial reduction has been carried out with

utmost care to stop the reduction in the hydroxylamine stage using boron tri-

fluoride and sodium borohydride, following a known procedure.[9]

General Procedure for the Nucelophilic Addition of 1-Methyl-2-

arylethyl Hydroxylamine to b-Nitrostyrenes

1-Methyl-2-arylethyl hydroxylamine (0.001 mol) was mixed with 0.001 mol

of substituted b-methyl-b-nitrostyrene and ground well in a mortar. The

paste obtained was left at room temperature for 2 days. The solid was

product thrown out; the nitrone (viz, C-aryl-N-1-methyl-2-arylethylamine-

N-oxide) was scratched with petroleum ether to remove the impurities. The

resulting nitrone was recrystallized from aqueous ethanol.

ACKNOWLEDGMENT

The authors thank the Department of Science and Technology, New Delhi, for

the NMR facility. One of the authors (C. A.) thanks the University Grants

Commission, New Delhi, for assistance under the Faculty Improvement

Program.

Scheme 4.

C. Amutha and S. Muthusubramanian336

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REFERENCES

1. Ono, N.; Miyake, H.; Kamimura, A.; Hamamota, I.; Tamuri, R.; Kaji, A. Denitro-hydrogenation of aliphatic nitro compounds a new use of aliphatic nitrocompounds as radical precursors. Tetrahedron 1985, 41, 4013.

2. (a) Kobayashi, N.; Iwai, K. Asymmetric addition of thioglycolic acid tonitro olefins catalyzed by cinchona alkaloids. J. Org. Chem. 1981, 46, 1823;(b) Functional polymers. 6. Unusual catalysis of polymeric cinchona alkaloidsin asymmetric reaction. Tetrahedron Lett. 1980, 21, 2167.

3. Worrall, D. E. The action of ammonia and aromatic amines on 4–methylnitro-styrene and related compounds. J. Am. Chem. Soc. 1938, 60, 2841.

4. Worrall, D. E. The addition of amino and hydrazino bases to nitrostyrene. J. Am.Chem. Soc. 1927, 49, 1598.

5. Khlestkin, V. K.; Mazhukin, D. G. Recent advances in the application of N,0–dia-lkylhydroxylamines in organic chemistry. Curr. Org. Chem. 2003, 7, 967.

6. Makhova, N. N.; Petukhova, V. Y.; Khmelnitskii, L. I. Reactions of 0–substitutedhydroxylamines with aldimines and primary aliphatic amines in the synthesis ofdiaziridines. Russ. Chem. Bull. 1982, 31, 2052.

7. Pai, V.; Bloomfield, S. F.; Gorrod, J. W. Mutagenicity of N–hydroxylamines andN–hydroxycarbamates towards strains of Escherichia coli and Salmonellatyphimurium. Fundamental and Molecular Mechanisms of Mutagenisis 1985,151, 201.

8. Boyland, E. The mechanism of tumor induction by aromatic amines and other car-cinogens. J. Cancer Res. Clin. Oncol. 1963, 65, 378.

9. Kabalka, G. W.; Varma, R. S. Syntheses and selected reductions of conjugatednitroalkanes. A Review. Org. Prepn. Proced. Internatl. 1987, 19, 285.

10. Alles, G. A. dl–Beta–phenylisopropyamines. J. Am. Chem. Soc. 1932, 54, 271.11. (a) Worrall, D. E. The addition of aromatic amines to bromonitrostyrene. J. Am.

Chem. Soc. 1921, 43, 919; (b) Worrall, D. E. Some reactions of unsaturatednitro compounds derived from terephthalaldehyde. J. Am. Chem. Soc. 1940,62, 3253.

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