Synlett 2007(5): 0812-0814  
DOI: 10.1055/s-2007-970781
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Novel One-Pot Synthesis of Unsymmetrical Acyclic Imides

Zohreh Habibia, Peyman Salehi*b, Mohammad Ali Zolfigolc, Maryam Yousefia
a Department of Chemistry, Shahid Beheshti University, Evin, Tehran 19839-63113, Iran
b Department of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, PO Box 19835-389, Evin, Tehran, Iran
Fax: +98(21)22431783; e-Mail: p-salehi@sbu.ac.ir;
c Department of Chemistry, Faculty of Science, Bu-Ali Sina University, Hamadan 65174, Iran
Further Information

Publication History

Received 21 April 2006
Publication Date:
08 March 2007 (online)

Abstract

A new and convenient method was found for the one-pot synthesis of symmetrical and unsymmetrical linear imides by ­reaction of aliphatic and aromatic nitriles with acyclic carboxylic anhydrides in the presence of silica sulfuric acid as an active and ­recyclable reagent.

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General Procedure for Liquid Nitriles
A mixture of 50 mmol of nitrile, silica sulfuric acid (0.18 g, equal to 1.36 mmol H+) and 1 mmol of carboxylic anhydride was heated in a 25 mL round-bottomed flask at 60-70 °C. The reactions were completed within 6-8 h as monitored by TLC (eluent, EtOAc-PE, 1:1). The mixture was filtered and solvent was evaporated under reduced pressure. A solution of NaHCO3 in H2O (1%, 10 mL) was added and the mixture was extracted with Et2O (3 × 25 mL). The organic layer was separated and dried over Na2SO4. When necessary, the crude product was purified by preparative TLC on silica gel.
General Procedure for Solid Nitriles
In a round-bottomed flask the solid nitrile (1 mmol), car-boxylic anhydride (1 mmol) and silica sulfuric acid (0.18 g, equal to 1.36 mmol H+) were mixed thoroughly. The flask was heated at 40-50 °C with concomitant stirring. After completion of the reaction confirmed by TLC (eluent: EtOAc-PE, 1:9), EtOAc (15 mL) was added and filtered. The filtrate was concentrated and purified by preparative TLC.

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Spectroscopic Data for Entries 1-16
N-Acetylacetamide (entry 1): white solid, mp 73-74 °C. 1H NMR (300 MHz, CDCl3): δ = 2.07 (s, 6 H), 8.72 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 24.91, 171.96. IR (KBr): 3410, 3265, 3215, 1732 cm-1. MS (EI): m/z (rel. intensity) = 101 (10) [M+], 72 (35), 58 (100).
N-Pentanoylacetamide (entry 2): white solid, mp 62-64 °C. 1H NMR (300 MHz, CDCl3): δ = 0.94 (t, J = 7.3 Hz, 3 H), 1.33-1.45 (m, 2 H), 1.60-1.70 (m, 2 H), 2.38 (s, 3 H), 2.52 (t, J = 7.4 Hz, 2 H), 8.57 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 13.75, 22.17, 25.12, 26.45, 37.03, 172.41, 174.03. IR (KBr): 3260, 3230, 1729 cm-1. MS (EI): m/z (rel. intensity) = 144 (41) [M+], 114 (25), 101 (58), 59 (82), 43 (100).
N-Acetylpropionamide (entry 3): white solid, mp 85-86 °C. 1H NMR (300 MHz, CDCl3): δ = 0.93 (t, J = 7.4 Hz, 3 H), 2.11 (s, 3 H), 2.32 (q, J = 7.4 Hz, 2 H), 8.25 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 8.37, 25.10, 29.69, 30.63, 172.20, 174.63. IR (KBr): 3265, 3236, 1727 cm-1. MS (EI): m/z (rel. intensity) = 115 (50) [M+], 97 (25), 71 (81), 57 (100). Anal. Calcd for C5H9NO2: C, 52.16; H, 7.88; N, 12.17; O, 27.79. Found: C, 52.08; H, 7.79; N, 12.09; O, 27.74.
N-Butyrylpropionamide (entry 4): white solid, mp 109-110 °C. 1H NMR (300 MHz, CDCl3): δ = 0.99 (t, J = 7.4 Hz, 3 H), 1.17 (t, J = 7.4 Hz, 3 H), 1.65-1.73 (m, 2 H), 2.58 (t, J = 7.2 Hz, 2 H), 2.66 (q, J = 7.1 Hz, 2 H), 8.84 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 8.35, 13.62, 17.86, 30.76, 39.27, 174.18, 175.21. IR (KBr): 3260, 3227, 1731 cm-1. MS (EI): m/z (rel. intensity) = 144 (12) [M+], 115 (25), 87 (28), 74 (80), 57 (100).
N-Butyrylisobutyramide (entry 5): white solid, mp 108-109 °C. 1H NMR (300 MHz, CDCl3): δ = 0.72 (t, J = 7.4 Hz, 3 H), 0.95 (d, J = 6.9 Hz, 6 H), 1.37-1.48 (m, 2 H), 2.45 (t, J = 7.4 Hz, 2 H), 2.49-2.56 (m, 1 H), 7.90 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 13.63, 17.72, 18.80, 35.86, 39.32, 175.64, 177.57. IR (KBr): 3260, 3234, 1727 cm-1. MS (EI): m/z (rel. intensity) = 157 (40) [M+], 88 (62), 71(100), 43 (81).
N-Acetyl-2-chloroacetamide (entry 6): white solid, mp 114-115 °C. 1H NMR (300 MHz, CDCl3): δ = 2.43 (s, 3 H), 4.28 (s, 2 H), 8.67 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 24.91, 43.66, 166.83, 171.31. IR (KBr): 3260, 3245, 1740 cm-1. MS (EI): m/z (rel. intensity) = 137 (11) [M + 2], 135 (34) [M+], 93 (20), 43(100).
N-Butyryl-2-chloroacetamide (entry 7): white solid, mp 111-112 °C. 1H NMR (300 MHz, CDCl3): δ = 1.00 (t, J = 7.4 Hz, 3 H), 1.70 (m, 2 H), 2.64 (t, J = 7.3 Hz, 2 H), 4.35 (s, 2 H), 8.51 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 13.54, 17.67, 39.05, 44.11, 167.30, 173.75. IR (KBr): 3255, 3242, 1740 cm-1. MS (EI): m/z (rel. intensity) = 165 (5) [M + 2], 163 (16) [M+], 135 (77), 114 (35), 71 (100), 43 (80).
N-Pentanoyl-2-chloroacetamide (entry 8): white solid, mp 104-105 °C. 1H NMR (300 MHz, CDCl3): δ = 0.95 (t, J = 7.3 Hz, 3 H), 1.34-1.46 (m, 2 H), 1.61-1.71 (m, 2 H), 2.66 (t, J = 7.4 Hz, 2 H), 4.33 (s, 2 H), 8.53 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 13.76, 22.15, 26.22, 36.99, 44.01, 166.97, 173.76. IR (KBr): 3260, 3235, 1739 cm-1. MS (EI): m/z (rel. intensity) = 179 (3) [M + 2], 177 (10) [M+], 135 (30), 107(33), 85 (100), 57 (88). Anal. Calcd for C7H12ClNO2: C, 47.33; H, 6.81; Cl, 19.96; N, 7.89; O, 18.01. Found: C, 47.03; H, 6.77; N, 7.81; O, 17.95.
N-Acetylbenzamide (entry 9): white solid, mp 112-114 °C. 1H NMR (300 MHz, CDCl3): δ = 2.39 (s, 3 H), 7.21-7.63 (m, 5 H), 8.44 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 25.47, 127.58, 129.08, 132.72, 133.30, 165.53, 173.15. IR (KBr): 3295, 1722 cm-1. MS (EI): m/z (rel. intensity) = 163 (10) [M+], 105 (100), 77 (78).
N-Acetyl-4-methylbenzamide (entry 10): white solid, mp 103-104 °C. 1H NMR (300 MHz, CDCl3): d = 2.45 (s, 3 H), 2.63 (s, 3 H), 7.32 (d, J = 8.0 Hz, 2 H), 7.75 (d, J = 8.2 Hz, 2 H), 8.59 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 21.59, 25.65, 127.93, 129.58, 129.80, 144.08, 165.84, 174.10. IR (KBr): 3395, 3285, 1709 cm-1. MS (EI): m/z (rel. inten-sity) = 177 (25) [M+], 162 (30), 119 (100), 91 (80), 65 (52). Anal. Calcd for C10H11NO2: C, 67.78; H, 6.26; N, 7.9; O, 18.06. Found: C, 67.62; H, 5.83; N, 8.00; O, 18.54.
N-Butyryl-4-methylbenzamide (entry 11): white solid, mp 87-88 °C. 1H NMR (300 MHz, CDCl3): δ = 1.04 (t, J = 7.3 Hz, 3 H), 1.73-1.82 (m, 2 H), 2.44 (s, 3 H), 7.31 (d, J = 8.0 Hz, 2 H), 7.76 (d, J = 8.0 Hz, 2 H), 8.64 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 13.74, 17.59, 21.59, 39.42, 127.69, 129.65, 130.00, 144.05, 165.37, 176.24. IR (KBr): 3270, 2950, 2935, 1710 cm-1. MS (EI): m/z (rel. intensity) = 205(32) [M+], 136 (20), 119 (100), 91 (33). Anal. Calcd for C12H15NO2: C, 70.22; H, 7.37; N, 6.82; O, 15.59. Found: C, 69.95; H, 7.01; N, 6.79; O, 15.52.
N-Pentanoyl-4-methylbenzamide (entry 12): white solid, mp 101-102 °C. 1H NMR (300 MHz, CDCl3): δ = 0.97 (t, J = 7.3 Hz, 3 H), 1.38-1.48 (m, 2 H), 1.66-1.76 (m, 2 H), 2.44 (s, 3 H), 3.02 (t, J = 7.5 Hz, 2 H), 7.31 (d, J = 7.9 Hz, 2 H), 7.79 (d, J = 8.2 Hz, 2 H), 8.53 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 13.89, 21.59, 22.32, 26.27, 37.30, 127.73, 129.65, 130.04, 144.04, 165.40, 176.46. IR (KBr): 3280, 2920, 2924, 1699 cm-1. MS (EI): m/z (rel. intensity) = 219 (34) [M+], 136 (20), 119 (100), 91 (50).
N-Acetyl-4-nitrobenzamide (entry 13): white solid, mp 118 °C. 1H NMR (300 MHz, CDCl3): δ = 2.33 (s, 3 H), 4.07 (s, 2 H), 7.47 (d, J = 8.5 Hz, 2 H), 8.1 (br s, 1 H), 8.23 (d, J = 8.6 Hz, 2 H). 13C NMR (75 MHz, CDCl3): δ = 25.08, 41.06, 124.00, 130.57, 140.63, 147.33, 170.66, 171.98. IR (KBr): 3435, 3250, 2990, 1732 cm-1. MS (EI): m/z (rel. intensity) = 222 (11) [M+], 163 (88), 137 (30), 43 (100). Anal. Calcd for C10H10N2O4: C, 54.05; H, 4.54; N, 12.61; O, 28.80. Found: C, 54.02; H, 4.50; N, 12.55; O, 28.77.
N-Butyryl-4-nitrobenzamide (entry 14): white solid, mp 122 °C. 1H NMR (300 MHz, CDCl3): δ = 0.99 (t, J = 7.4 Hz, 3 H), 1.64-1.74 (m, 2 H), 2.50 (t, J = 7.3 Hz, 2 H), 4.16 (s, 2 H) 7.47 (d, J = 8.8 Hz, 2 H), 8.09 (br s, 1 H), 8.22 (d, J = 8.8 Hz, 2 H). 13C NMR (75 MHz, CDCl3): δ = 13.56, 17.80, 39.30, 43.51, 123.74, 130.60, 140.87, 147.27, 171.25, 174.20. IR (KBr): 3205, 3000, 1729 cm-1. MS (EI): m/z (rel. intensity) = 250 (10) [M+], 180 (30), 163 (50), 133 (25), 88 (50), 71 (100), 43 (75).
N-Acetyl-3-chlorobenzamide (entry 15): white solid, mp 105-107 °C. 1H NMR (300 MHz, CDCl3): δ = 2.63 (s, 3 H), 7.45-7.49 (m, 3 H), 7.88 (s, 1 H), 8.71 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 25.65, 125.75, 128.24, 130.23, 133.24, 134.41, 135.27, 164.63, 173.81. IR (KBr): 3418, 3196, 1718 cm-1. MS (EI): m/z (rel. intensity) = 199 (8) [M + 2], 197 (16) [M+], 168 (18), 139 (100), 111 (25), 75 (20), 71 (100), 43 (50).
N-Butyryl-3-chlorobenzamide (entry 16): white solid, mp 97-100 °C. 1H NMR (300 MHz, CDCl3): δ = 1.04 (t, J = 7.4 Hz, 3 H), 1.73-1.80 (m, 2 H), 2.98 (t, J = 7.4 Hz, 2 H), 7.44-7.73 (m, 3 H), 7.87 (s, 1 H), 8.54 (br s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 13.71, 17.46, 39.58, 125.87, 128.22, 129.78, 130.16, 133.13, 133.50, 134.59, 135.20, 164.55, 176.88. IR (KBr): 3420, 3185, 2920, 1710 cm-1. MS (EI): m/z (rel. intensity) = 227 (2) [M + 2], 225 (7) [M+], 196 (30), 156 (75), 139 (100), 111 (75), 75 (50), 43 (88).