Synlett 2010(11): 1666-1668  
DOI: 10.1055/s-0029-1219956
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of Diethyl α-(o-Nitroaryl)phosphoglycines via Oxidative Nucleophilic Substitution of Hydrogen in Nitroarenes

Mieczysław Mąkosza*, Daniel Sulikowski
Institute of Organic Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw, Poland
Fax: +48(22)6326681; e-Mail: icho-s@icho.edu.pl;
Further Information

Publication History

Received 15 April 2010
Publication Date:
04 June 2010 (online)

Abstract

The carbanion of protected diethyl phosphoglycinate adds to nitroarenes in liquid ammonia in ortho position to the nitro group. Subsequent oxidation of the resulting adduct σH with potassium permanganate gave N-protected diethyl α-(o-nitroaryl)phosphoglycinates.

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General Procedure
To liquid NH3 (15 mL) at -78 ˚C a solution of nitroarene (2.0 mmol) and 1b (269 mg, 1.0 mmol) was added followed by dropwise addition of KOt-Bu in THF (1.05 mL, 1.00 M, 1.05 mmol) over 5 min. The reaction mixture was stirred at this temperature for 30 min and then solid KMNO4 (156 mg, 1.0 mmol) was added. After 5 min reaction was quenched by addition of NH4Cl (500 mg), and the mixture was left to evaporation of NH3. The residue was treated with H2O (50 mL) and EtOAc (50 mL) and filtered through a pad of Celite. The organic layer was separated, dried, and evaporated. Products were isolated by column chromatography (EtOAc-hexane).

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Selected Analytical Data
Diethyl N -(1,3-Ditiholan-2-ylidene)-α-(2-nitrophenyl)-phosphoglycinate (2a)
Solidifying oil. IR (film, CH2Cl2): νmax = 2986, 2905, 1589, 1534, 1355, 1245, 1026, 572 cm. ¹H NMR (400 MHz, CDCl3): δ = 8.00 (m, 1 H), 7.90 (m, 1 H), 7.61 (m, 1 H), 7.41 (m, 1 H), 4.50 (s, 1 H), 5.96 (d, J = 18.8 Hz), 4.11-4.00 (m, 4 H), 3.64-3.40 (m, 4 H), 1.26-1.21 (m, 6 H). ¹³C NMR (100 MHz, CDCl3): δ = 175.6 (d, J = 19 Hz), 148.4 (d, J = 7 Hz), 132.9 (d, J = 4 Hz), 130.9 (d, J = 7 Hz), 130.7 (d, J = 4 Hz), 128.1 (d, J = 4 Hz), 124 (d, J = 3 Hz), 65.9 (d, J = 156 Hz), 63.4 (d, J = 15 Hz), 63.3 (d, J = 15 Hz), 38.1, 35.0, 16.3 (d, J = 10 Hz), 16.2 (d, J = 10 Hz). ³¹P NMR (162 MHz, CDCl3): δ = 18.1. ESI-LRMS (+): m/z 391 [M + H]+. Anal. Calcd for C14H19N2O5S2P: C, 43.07; H, 4.91; N, 7.18; S, 16.43. Found: C, 42.85; H, 4.90; N, 7.17; S, 16.55.
Diethyl N -(1,3-Dithiolan-2-ylidene)-α-(1-nitro-2-naphthyl)-phosphoglycinate (9b)
Oil. IR (film, CH2Cl2): νmax = 2983, 1581, 1528, 1254, 1049, 1020, 563 cm. ¹H NMR (400 MHz, CDCl3): δ = 8.05-7.95 (m, 2 H), 7.90-7.85 (m, 1 H), 7.76-7.71 (m, 1 H), 7.63-7.54 (m, 2 H), 5.15 (d, J = 18.0 Hz), 4.20-4.00 (m, 4 H), 3.65-3.51 (m, 2 H), 3.49-3.35 (m, 2 H), 1.28 (dt, J = 0.4, 7.1 Hz, 3 H), 1.22 (dt, J = 0.4, 7.1 Hz, 3 H). ¹³C NMR (100 MHz, CDCl3): δ = 175.7 (d, J = 19 Hz), 146.8 (d, J = 9 Hz), 133.0 (d, J = 2 Hz), 130.6 (d, J = 3 Hz), 128.4, 127.9 (d, J = 2 Hz), 127.4, 126.2 (d, J = 4 Hz), 126.0 (d, J = 6 Hz), 124.2 (d, J = 2 Hz), 121.8, 66.9 (d, J = 161 Hz), 63.6 (d, J = 8 Hz), 63.5 (d, J = 8 Hz), 38.2, 34.9, 16.2 (d, J = 6 Hz), 16.1 (d, J = 6 Hz). ³¹P NMR (162 MHz, CDCl3): δ = 17.6. ESI-LRMS (+): m/z 463 [M + H]+. Anal. Calcd for C18H21N2O5S2P: C, 49.08; H, 4.91; N, 6.36; S, 14.56. Found: C, 48.62; H, 4.93; N, 6.34; S, 14.45.

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The hydrolysis reactions were performed according to literature procedure, see ref. 15a.
Selected Analytical Data
Diethyl α-(5-Fluoro-2-nitrophenyl)phosphoglycinate (3c)
Oil. IR (film, CH2Cl2): νmax = 3250, 2987, 1689, 1589, 1532, 1351, 1236 cm. ¹H NMR (400 MHz, CDCl3): δ = 8.27 (s, 1 H), 8.00 (ddd, J = 0.4, 5.1, 9.0 Hz, 1 H), 7.64 (dt, J = 2.7, 9.5 Hz, 1 H), 7.13-7.09 (m, 1 H), 5.52 (d, J = 21.5 Hz), 4.26-4.00 (m, 4 H), 2.95 (br s, 1 H), 1.29 (t, J = 7.0 Hz, 3 H), 1.17 (t, J = 7.0 Hz, 3 H). ¹³C NMR (100 MHz, CDCl3): δ = 164.9 (d, J = 204 Hz), 160.9 (d, J = 7.4 Hz), 144.7 (dd, J = 2.3, 5.0 Hz), 137.0 (d, J = 6.6 Hz), 127.9 (dd, J = 1.6, 7.8 Hz), 116.5 (dd, J = 2.4, 3.5 Hz), 115.4 (dd, J = 2.3, 18.6 Hz), 63.6 (d, J = 5.5 Hz), 63.5 (d, J = 5.5 Hz), 47.8 (d, J = 118 Hz), 16.3 (d, J = 2.5 Hz), 16.2 (d, J = 2.5 Hz). ³¹P NMR (162 MHz, CDCl3): δ = 22.0. ESI-LRMS (+): 357 [M + Na]+. Anal. Calcd for C12H16N2O6PF: C, 43.12; H, 4.83; N, 8.38. Found: C, 43.16; H, 4.83; N, 8.30.