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Synlett 2008(5): 675-678  
DOI: 10.1055/s-2008-1032097
LETTER
© Georg Thieme Verlag Stuttgart · New York

Aerobic Photooxidation of Benzylamide in the Presence of Catalytic Iodine

Hiroki Nakayama, Akichika Itoh*
Gifu Pharmaceutical University, Mitahora-higashi, Gifu 502-8585, Japan
e-Mail: itoha@gifu-pu.ac.jp;
Further Information

Publication History

Received 16 December 2007
Publication Date:
26 February 2008 (online)

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Abstract

Benzylamides were found to be oxidized to the corresponding imides in the presence of molecular oxygen and catalytic iodine under photoirradiation.

Key words

aerobic - amide - imide - iodine - photooxidations

    References and Notes

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11

A typical procedure follows: A dry EtOAc solution (5 mL) of the N-benzylacetamide (1, 0.3 mmol) and I2 (0.003 mmol) in a pyrex test tube equipped with an O2 balloon, was irradiated without stirring condition for 48 h with a 500 W Xenon lamp, which was set from the test tube in the distance of 45 cm. The reaction mixture was concentrated under reduced pressure, and the pure product was obtained by preparative TLC.N -Acetyl-4-methoxybenzamide (4) 1H NMR (400 MHz, CDCl3): δ = 9.19 (s, 1 H), 7.85 (d, J = 9.0 Hz, 2 H), 6.93 (d, J = 9.0 Hz, 2 H), 3.83 (s, 3 H), 2.56 (s, 3 H). IR (KBr): 3233, 1712, 1689, 1607, 1472, 1251, 854 cm-1. HRMS (EI+): m/z calcd for C10H11NO3 [M+]: 193.07390; found: 193.07484.N -Acetyl-4-methylbenzamide (6) 1H NMR (400 MHz, CDCl3): δ = 9.17 (s, 1 H), 7.80 (d, J = 8.3 Hz, 2 H), 7.29 (d, J = 7.8 Hz, 2 H), 2.60 (s, 3 H), 2.42 (s, 3 H). IR (KBr): 3263, 1725, 1611, 1506, 1231 cm-1. HRMS (EI+): m/z calcd for C10H11 NO2 [M+]: 177.07898; found: 177.07970.N -Acetyl-4-chlorobenzamide (8) 1H NMR (400 MHz, CDCl3): δ = 9.44 (s, 1 H), 7.88 (d, J = 8.8 Hz, 2 H), 7.48 (d, J = 8.8 Hz, 2 H), 2.61 (s, 3 H). IR (KBr): 3263, 1710, 1689, 1592, 1468, 750 cm-1. HRMS (EI+): m/z calcd for C10H11NO3 [M+]: 197.02435; found: 197.02382.N -(2-Methybenzyl)acetamide (9) 1H NMR (400 MHz, CDCl3): δ = 7.23-7.19 (m, 4 H), 5.56 (s, 1 H), 4.43 (d, J = 5.3 Hz, 2 H), 2.32 (s, 3 H), 2.01 (s, 3 H). 13C NMR (400 MHz, CDCl3): δ = 169.7, 136.5, 135.8, 130.6, 128.7, 127.8, 126.2, 41.9, 23.1, 19.0. IR (KBr): 3293, 1637, 1547, 742 cm-1. Anal. Calcd for C10H13NO: C, 73.59; H, 8.03; N, 8.58. Found: C, 73.53; H, 8.14; N, 8.63.N -Acetyl-2-methylbenzamide (10) 1H NMR (400 MHz, CDCl3): δ = 8.50 (s, 1 H), 7.41 (d, J = 5.3 Hz, 1 H), 7.36 (t, J = 7.6 Hz, 1 H), 7.24-7.22 (m, 2 H), 2.52 (s, 3 H), 2.44 (s, 3 H). 13C NMR (400 MHz, CDCl3): δ = 172.9, 167.9, 137.4, 133.9, 131.7, 131.5, 126.9, 126.0, 23.4, 20.0. IR (KBr): 3248, 1727, 1506, 1221, 738 cm-1. Anal. Calcd for C10H11NO2: C, 67.63; H, 6.26; N,7.90. Found: C, 67.63; H, 6.27; N, 7.75.N -(1-Naphthylmethyl)acetamide (17) 1H NMR (400 MHz, CDCl3): δ = 7.99 (d, J = 7.7 Hz, 1 H), 7.86 (d, J = 7.4 Hz, 1 H), 7.79 (t, J = 4.8 Hz, 1 H), 7.55-7.48 (m, 2 H), 7.40 (d, J = 4.8 Hz, 2 H), 5.87 (s, 1 H), 4.83 (d, J = 5.3 Hz, 2 H), 1.96 (s, 3 H). 13C NMR (400 MHz, CDCl3): δ = 169.7, 133.8, 133.5, 131.4, 128.7, 128.6, 126.7, 126.6, 126.0, 125.3, 123.5, 41.8, 23.1. IR (KBr): 3301, 1638, 1553, 1290, 780, 606 cm-1. Anal. Calcd for C13H13NO: C, 78.36; H, 6.58; N, 7.03. Found: C, 78.47; H, 6.71; N, 6.96.N -Acetyl-1-naphthalenecarboxamide (18) 1H NMR (400 MHz, CDCl3): δ = 8.64 (s, 1 H), 8.32 (d, J = 8.3 Hz, 1 H), 7.99 (d, J = 8.3 Hz, 1 H), 7.89 (d, J = 7.8 Hz, 1 H), 7.70 (d, J = 7.1 Hz, 1 H), 7.61-7.54 (m, 2 H), 7.48 (t, J = 7.3 Hz, 1 H), 2.64 (s, 3 H). IR (KBr): 3263, 1715, 1686, 1487, 1244, 779 cm-1. HRMS (EI+): m/z calcd for C15H13NO3 [M+]: 213.07898; found: 213.07983.

12

In the presence of 1 equiv of galvinoxyl, no oxidation proceeded when 1 was used as starting material.