Synlett 2008(20): 3133-3136  
DOI: 10.1055/s-0028-1087277
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

A Mild and Efficient Catalytic Strecker Reaction of N-Alkoxycarbonylamino Sulfones with Trimethylsilyl Cyanide Using Indium(III) Chloride: A Facile Synthesis of α-Aminonitriles [¹]

Biswanath Das*, Kongara Damodar, Boddu Shashikanth, Yallamalla Srinivas, Itikala Kalavathi
Organic Chemistry Division - I, Indian Institute of Chemical Technology, Hyderabad-500 007, India
Fax: +91(40)7160512; e-Mail: biswanathdas@yahoo.com;
Further Information

Publication History

Received 6 August 2008
Publication Date:
26 November 2008 (online)

Abstract

The Strecker reaction of N-alkoxycarbonylamino ­sulfones with trimethylsilyl cyanide in the presence of catalytic amount of indium(III) chloride at room temperature produces the corresponding protected α-aminonitriles in high yields.

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Part 179 in the series ‘Studies on novel synthetic methodologies’.

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Part 179 in the series ‘Studies on novel synthetic methodologies’.

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General Procedure for the Synthesis of α-Aminonitriles
Trimethylsilyl cyanide (2, 120 mg, 1.2 mmol) was added dropwise to a solution of an N-alkoxycabonylamino sulfone 1 (1 mmol) and InCl3 (22.1 mg, 10 mol%) in CH2Cl2 (5 mL) under nitrogen. The mixture was stirred, and the reaction was monitored by TLC. After completion, the reaction was quenched with distilled H2O (5 mL) and the mixture was extracted with EtOAc (3 ×10 mL). The combined organic portions were washed with H2O (2 × 10 mL) and sat. aq NH4Cl solution (2 × 10 mL), dried over anhyd Na2SO4, and concentrated under vacuum. The crude product was subjected to column chromatography (silica gel, hexane-EtOAc = 85:15 to 90:10) to obtain pure protected α-aminonitrile.
Spectroscopic Data of some Representative Products
2-(Benzyloxycarbonylamino)-2-(phenyl)acetonitrile (3a)
White solid; mp 107-109 ˚C. IR (KBr): 3278, 3031, 1694, 1521, 1451 cm. ¹H NMR (200 MHz, CDCl3): δ = 7.55-7.24 (10 H, m), 5.80 (1 H, br d, J = 8.7 Hz), 5.37 (1 H, br d, J = 8.7 Hz), 5.12 (2H, s). ¹³C NMR (50 MHz, CDCl3): δ = 155.2, 135.7, 133.3, 129.9, 129.6, 128.9, 128.7, 128.5, 127.1, 117.6, 68.2, 46.8. MS-FAB: m/z = 267 [M + H]+. ESI-HRMS: m/z calcd for C16H14N2O2Na [M + Na]+: 289.0952; found: 289.0951.
2-(Benzyloxycarbonylamino)-2-(4-methoxyphenyl)-acetonitrile (3g)
White solid; mp 113-115 ˚C. IR (KBr): 3296, 1688, 1612, 1519, 1253 cm. ¹H NMR (200 MHz, CDCl3): δ = 7.43 (2 H, d, J = 8.0 Hz), 7.40-7.31 (5 H, m), 6.92 (2 H, d, J = 8.0 Hz), 5.76 (1 H, d, J = 8.0 Hz), 5.22 (1 H, d, J = 8.0 Hz), 5.18 (2 H, s), 3.82 (3 H, s). ¹³C NMR (50 MHz, CDCl3): δ = 160.7, 155.2, 135.7, 128.8, 128.7, 128.6, 128.5, 125.2, 117.8, 114.9, 68.1, 55.6, 46.3. ESI-MS: m/z = 297 [M + H]+, 319 [M+Na]+. ESI-HRMS: m/z calcd for C17H16N2O3Na [M + Na]+: 319.1058; found: 319.1069.
2-(Benzyloxycarbonylamino)-2-(3-nitrophenyl)aceto-nitrile (3j) White solid; mp 112-114 ˚C. IR (KBr): 3280, 3057, 1692, 1532 cm. ¹H NMR (200 MHz, CDCl3): δ = 8.37 (1 H, t, J = 7.0 Hz), 8.33 (1 H, dd, J = 8.0, 2.0 Hz), 7.83 (1 H, dd, J = 8.0, 2.0 Hz), 7.62 (1 H, t, J = 8.0 Hz), 7.35 (5 H, br s), 5.95 (1 H, br d, J = 8.0 Hz), 5.52 (1 H, d, J = 8.0 Hz), 5.17 (2 H, s). ¹³C NMR (50 MHz, CDCl3): δ = 155.2, 148.9, 135.6, 135.3, 133.0, 130.7, 128.7, 128.5, 124.7, 122.2, 116.6, 68.5, 46.0. MS-FAB: m/z = 311 [M]+. ESI-HRMS: m/z calcd for C16H13N3O4Na [M + Na]+: 334.0803; found: 334.0820.
2-(Benzyloxycarbonylamino)-2-(2-naphthyl)aceto-nitrile (3l)
White solid; mp 133-135 ˚C. IR(neat): 3283, 1690, 1517, 1289 cm. ¹H NMR (200 MHz, CDCl3): δ = 7.98 (1 H, d, J = 2.0 Hz), 7.90-7.79 (3 H, m), 7.58-7.45 (3 H, m), 7.38-7.27 (5 H, m), 5.99 (1 H, d, J = 8.0 Hz), 5.39 (1 H, d, J = 8.0 Hz), 5.18 (2 H, s). ¹³C NMR (50 MHz, CDCl3): δ = 155.1, 135.5, 133.5, 133.0, 130.2, 129.6, 128.7, 128.6, 128.3, 128.2, 127.8, 127.3, 127.1, 126.5, 123.9, 117.5, 68.0, 46.8. ESI-MS: m/z = 317 [M + H]+. ESI-HRMS: m/z calcd for C20H16N2O2Na [M + Na]+: 339.1109; found: 339.1125.
2-(Benzyloxycarbonylamino)-2-(2-furyl)acetonitrile (3m)
Pale grey solid; mp 104-106 ˚C. IR(neat): 3270, 1694, 1532, 1255 cm. ¹H NMR (200 MHz, CDCl3): δ = 7.42 (1 H, d, J = 1.5 Hz), 7.39-7.22 (5 H, m), 6.52 (1 H, d, J = 3.0 Hz), 6.38 (1 H, dd, J = 3.0, 1.5 Hz), 5.89 (1 H, d, J = 8.0 Hz), 5.45 (1 H, d, J = 8.0 Hz), 5.14 (2 H, s). ¹³C NMR (50 MHz, CDCl3): δ = 154.8, 145.0, 144.1, 135.3, 128.6, 128.5, 128.2, 115.6, 110.9, 109.8, 68.0, 40.5. ESI-MS: m/z = 257 [M + H]+. ESI-HRMS: m/z calcd for C14H12N2O3Na [M + Na]+: 279.0745; found: 279.0742.
2-(Benzyloxycarbonylamino)-3-methylbutyronitrile (3r)
Colorless oil. IR(neat): 3324, 3035, 1706, 1527, 1266, 1237 cm. ¹H NMR (200 MHz, CDCl3): δ = 7.35-7.26 (5 H, br s), 5.16 (1 H, br d, J = 8.0 Hz), 5.12 (2 H, s), 4.50 (1 H, t, J = 8.0 Hz), 2.03 (1 H, m), 1.11 (3 H, d, J = 7.0 Hz), 1.07 (3 H, d, J = 7.0 Hz). ¹³C NMR (50 MHz, CDCl3): δ = 155.5, 135.8, 128.8, 128.7, 127.0, 117.9, 67.8, 49.0, 31.8, 18.9, 18.2. MS-FAB: m/z 233 [M + H]+. ESI-HRMS: m/z calcd for C13H16N2O2Na [M + Na]+: 255.1109; found: 255.1102.