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Synlett 2003(5): 0714-0716
DOI: 10.1055/s-2003-38351
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

One-flask Conversion of N-Aryliminophosphoranes into N1, N2, N3-Triarylguanidines Promoted by TBAF.

Pedro Molina*, Enrique Aller, Angeles Lorenzo
Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia, Campus de Espinardo, 30071, Murcia, Spain
Fax: +34(968)364149; e-Mail: pmolina@um.es;
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Publication History

Received 8 November 2002
Publication Date:
28 March 2003 (online)

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Abstract

N-Aryliminophosphoranes were converted into N1, N2, N3-triarylguanidines in synthetically useful yields by reactions with isocyanates followed by treatment of resulting N1, N2-diarylcarbodiimide with aromatic amines in the presence of TBAF.

Key words

iminophosphoranes - isocyanates - carbodiimides guanidines - tetrabutylammonium fluoride

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Typical experimental procedure. To a mixture of the appropriate iminophosphorane 1 (1.16 mmol), anhydrous MgSO4 (2 g) and dry THF (5 mL) was added an equimolar amount of the adequate isocyanate 2 under N2. The reaction mixture was stirred at r.t. for 1 h. Afterwards, the aromatic amine 4 (1.74 mmol) and 1 M TBAF in THF (1.8 mL, 1.8 mmol) were added and stirring was continued for 10 min. The crude was poured into Na2HPO4 buffer (pH = 7, 15 mL) and extracted with EtOAc (3 ¥ 25 mL). The combined organic layers were dried (MgSO4), filtered, and concentrated to dryness. The crude solid was chromato-graphed on a silica gel column using hexane-EtOAc (2:1) as eluent to give 5.

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Compound 5a: mp 141-142 °C (white prisms); 1H NMR (300 MHz, DMSO) d 2.19 (s, 6 H, CH3), 6.67 (m, 1 H), 6.92 (m, 6 H), 7.11 (m, 4 H), 7.42 (d, 1 H, J = 7.8 Hz) 8.15 (s, 2 H, NH). 13C NMR (50.32 MHz, DMSO) d 20.32 (2 ¥ CH3), 117.23 (q), 119.31, 121.90, 123.01, 127.68, 128.82 (2 ¥ CH) 129.98, 132.17, 138.65 (q), 146.03 (q), 147.81 (q). MS (EI, 70 eV); m/z (%): 396 (M+ + 2, 10), 394 (M+, 16), 393 (37), 314 (28), 288 (37), 222 (56), 107 (100), 91 (44). C20H20BrN3 (382.305) calcd C, 62.83; H, 5.27; N, 10.98. Found C, 62.70; H, 5.35; N, 10.72.
Compound 5b: mp 115-116 °C (brown prisms); 1H NMR (300 MHz, DMSO) d 2.18 (s, 3 H, CH3), 3.66 (s, 3 H, CH3O), 6.69 (m, 1 H), 6.77 (d, 2 H, J = 9 Hz), 6.87 (m, 1 H), 6.96 (d, 2 H, J = 8.4 Hz), 7.05 (m, 1 H), 7.14 (m, 2 H,) 7.41 (d, 1 H, J = 7.8 Hz), 8.05 (s, 2 H, 2 ¥ NH). 13C NMR (50.32 MHz, DMSO) 20.30 (CH3), 55.13 (CH3O), 113.71 (CH), 117.33 (q), 119.33, 121.33, 121.83, 123.16, 127.70, 128.82, 129.90 (q), 132.15, 134.01 (q), 138.6 (q), 146.36 (q), 148.24 (q), 154.32 (q). MS (EI, 70 eV); m/z (%): 412 (M+ + 2, 6), 410 (M+, 8), 330 (20), 304 (17), 302 (18), 284 (14), 287 (17), 238 (28), 223 (27), 1237 (100), 91 (33), 77 (17). C20H20BrN3O (398.304) calcd C, 60.31; H, 5.06; N, 10.55. Found C, 60.50; H, 4.90; N, 10.79.
Compound 5c: mp 131-132 °C (white prisms); 1H NMR (300 MHz, CDC3) d 2.18 (s, 3 H, CH3), 6.69 (m, 1 H), 6.75 (d, 1 H), 6.75 (d, 2 H, J = 8.2 Hz), 7.07 (m, 1 H), 7.12 (d, 2 H, J = 8.4 Hz), 7.18 (d, 2 H J = 9 Hz), 7.43 (d, 2 H) 8.55 (s, 2 H) 13C NMR (50.32 MHz, DMSO) d 20.30 (CH3), 117.07 (q), 119.47, 120.48, 122.28 123.12, 127.76, 128.18, 128.88, 130.27 (q), 132.23 (q), 139.2 (q), 145,7 (q). MS (EI, 70 eV); m/z (%): 418 (M+ + 4, 7), 416 (M+ + 2, 28), 414 (M+, 50), 336 (26), 334 (47), 332 (8), 289 (31), 287 (35). 244 (26), 242 (58), 167 (27), 127 (36), 106 (100), 91 (39), 77 (38). C19H17BrClN3 (402.723) calcd C, 56.67; H, 4.25; N, 10.43. Found C, 56.49; H, 4.19; N, 10.65.
Compound 5d: mp 154-155 °C (yellow prisms); 1H NMR (300 MHz, CDCl3) d 2.38 (s, 3 H, CH3), 5.80 (s, 2 H), 6.91 (m, 1 H), 7.39 (m, 9 H), 8.16 (d, 2 H, J = 9.1 Hz), 8.16 (d, 2 H, J = 9.1 Hz). 13C NMR (50.32 MHz, CDCl3) d 20.88 (CH3), 116.24 (q), 120.44, 122.95, 124.19, 124.35, 125.18, 128.38, 130.34, 132.95, 134.94 (q), 135.85 (q), 141.11 (q), 142.07 (q), 145.04 (q), 150.77 (q). MS (EI, 70 eV); m/z (%):427 (M+ + 2, 12), 425(M+, 21), 345 (50), 286 (34), 253 (37), 171 (51), 106 (100), 90 (51). C19H17BrN4 O2 (413.274) calcd C, 55.22; H, 4.15; N, 13.56. Found C, 55.44; H, 4.28; N, 13.35.
Compound 5e: mp 146-147 °C (yellow prisms); 1H NMR (300 MHz, DMSO) d 2.18 (s, 3 H, CH3), 6.69 (m, 1 H), 6.75 (d,1 H), 6.71 (d, 2 H, J = 8.2 Hz), 7.07 (m, 1 H), 7.12 (d, 2 H, J = 8.4 Hz), 7.18 (d, 2 H, J = 9 Hz), 7.25 (d, 2 H, J = 9 Hz), 7.43 (d, 2 H), 8.55 (s, 2 H). 13C NMR (50.32 MHz, DMSO) d 20.30 (CH3), 117.07 (q), 119.47, 120.48, 122.28, 123.12, 127.76, 128.18, 128.88, 130.27 (q), 128.88, 132.23, 139.2 (q), 145.7 (q). (q). MS (EI, 70 eV); m/z (%): 412 (M+ + 2, 24), 410 (M+, 24), 366 (31), 354 (35), 349 (39), 289 (98), 272 (97), 210 (96), 196 (47), 170 (100), 154 (49), 148 (51), 104 (66), 77 (33). C17H15BrN4O2 (399.25) calcd C, 54.15; H, 4.15; N, 13.56. Found C, 54.09; H, 4.01, N, 13.68.
Compound 5f: mp 201-202 °C (white prisms); 1H NMR (300 MHz, DMSO) d 2.18 (s, 3 H, CH3), 6.69 (m, 1 H), 6.75 (d, 1 H), 6.75 (d, 2 H, J = 8.2 Hz), 7.07 (m, 1 H), 7.12 (d, 2 H, J = 8.4 Hz), 7.18 (d, 2 H J = 9 Hz), 7.43 (d, 2 H), 8.5 5 (s, 2 H) 13C NMR (50.32 MHz, DMSO) d 20.30 (CH3), 117.07 (q), 119.47, 120.48, 122.28 123.12, 127.76, 128.18, 128.88, 130.27 (q), 132.23 (q), 139.2 (q), 145,7 (q). MS (EI, 70 eV); m/z (%): 303 (M+, 87), 210 (51), 209 (89), 197 (100), 107 (61), 77 (95), C18H17N5 (303.362) calcd C, 71.27; H, 17.13; N, 23.08. Found C, 71.05; H, 16.92; N, 22.95.