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Synlett 2006(4): 0559-0562  
DOI: 10.1055/s-2006-932470
LETTER
© Georg Thieme Verlag Stuttgart · New York

Sodium Bis(trimethylsilyl)amide in the ‘One-Flask’ Transformation of ­Isocyanates to Cyanamides

Fung Fuh Wong*a, Chun-Yen Chenb, Mou-Yung Yehb,c
a Environment Sustainable Research Center, National Cheng Kung University, 500 Sec. 3 An-ming Rd., Tainan 709, Taiwan
Fax: +886(6)3840960; e-Mail: wong99@mail.ncku.edu.tw;
b Department of Chemistry, National Cheng Kung University, 1 Ta Hsueh Rd., Tainan 701, Taiwan
c Nan Jeon Institute of Technology, 178 Chaocin Rd., Yanshuei Township 737, Taiwan
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Publikationsverlauf

Received 1 November 2005
Publikationsdatum:
20. Februar 2006 (online)

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Abstract

Cyanamides were successfully prepared in a ‘one-flask’ reaction from isocyanates by use of sodium bis(trimethyl­silyl)amide as the deoxygenating agents in THF at room temperature.

Key words

isocyanates - cyanamides - 1,2-elimination - sodium bis(trimethylsilyl)amide

11

The results are being prepared for submission.

33

N-(Trimethylsilyliminomethylene)benzenamine (6): MS: m/z (relative intensity) = 190 (10) [M+], 188 (59), 172 (26), 160 (15), 156 (14), 144 (15), 140 (13), 128 (10), 119 (12), 115 (16), 103 (10), 93 (34), 91 (16), 87 (12), 77 (16), 65 (17), 57 (24), 44 (100), 40 (95), 39 (35).

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Compound 8: MS: m/z (relative intensity) = 137 (13) [M+], 119 (48), 106 (16), 93 (92), 91 (46), 77 (25), 65 (41), 43 (87), 40 (100), 39 (64).

36

The spectroscopic data of compound 9 are consistent with those of an authentic sample.

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Standard Procedure for the Formation of Cyanamides. A mixture of isocyanate (1.0 mmol) and sodium bis(trimethylsilyl)amide (1.0 M in THF, 1.5 or 3.0 mmol) was stirred in a two-necked flask at r.t. under nitrogen gas for 5 h. After the reaction was completed, the reaction mixture was diluted with H2O at r.t., and extracted with EtOAc (2 × 10 mL). The combined organic layers were washed with sat. aq NaCl (5 mL), dried over MgSO4, filtered, and concentrated under reduced pressure. The residue was purified by column chromatography (silica gel) to provide the desired cyanamide compound.
Compound 2a: 1H NMR (300 MHz, CDCl3): δ = 1.24 (d, 6 H, J = 6.27 Hz, CH3), 3.45 (s, 1 H, CH), 3.77 (br, 1 H, NH). 13C NMR (75 MHz, CDCl3): δ = 22.86, 47.99, 122.68. IR (diffuse reflectance): ν = 3212 (m), 2975 (s), 2214 (s, CºN), 1695 (m), 1537 (w), 1465 (m), 1388 (w), 1251 (w), 1183 (w), 1089 (w), 542 (w) cm-1.
Compound 2b: 1H NMR (300 MHz, CDCl3): δ = 5.21 (s, 2 H, CH2), 6.97-7.40 (m, 5 H, ArH). IR (diffuse reflectance): ν = 3320 (m), 3030 (s), 2930 (s), 2222 (m, CºN), 1670 (s), 1613 (s), 1542 (s), 1495 (s), 1454 (s), 1257 (s), 1137 (m), 1076 (m), 735 (s), 602 (w) cm-1.
Compound 2c: 1H NMR (300 MHz, CDCl3): δ = 1.14-1.55 (m, 6 H), 1.77-1.96 (m, 4 H), 3.08-3.12 (m, 1 H, CH), 3.43 (br, 1 H, NH). 13C NMR (75 MHz, CDCl3): δ = 24.59, 25.18, 32.57, 54.15, 115.89. IR (diffuse reflectance): ν = 3216 (m), 2932 (s), 2857 (s), 2217 (s, C≡N), 1694 (s), 1536 (s), 1452 (s), 1318 (m), 1146 (m), 1062 (m) cm-1.
Compound 2d: 1H NMR (300 MHz, CDCl3): δ = 4.07 (br, 1 H, NH), 6.81 (m, 1 H, ArH), 7.28-7.38 (m, 1 H, ArH), 7.41-7.64 (m, 2 H, ArH), 7.72-8.05 (m, 2 H, ArH). 13C NMR (75 MHz, CDCl3): δ = 109.79, 112.44, 119.04, 120.87, 123.72, 124.90, 125.89, 126.39, 128.59, 134.44, 142.10. IR (diffuse reflectance): ν = 3365 (m), 3051 (m), 2226 (w, CºN), 1694 (m), 1624 (s), 1577 (m), 1513 (m), 1458 (m), 1405 (m), 1287 (m), 1218 (m), 854 (w), 770 (s) cm-1.
Compound 2e: 1H NMR (300 MHz, CDCl3): δ = 5.75 (br, 1 H, NH), 7.03 (d, 2 H, J = 8.51 Hz, ArH), 7.11 (t, 1 H, J = 7.52 Hz, ArH), 7.32 (t, 2 H, J = 7.53 Hz, ArH). 13C NMR (75 MHz, CDCl3): δ = 111.23, 114.38, 122.17, 129.17, 139.63. IR (diffuse reflectance): ν = 3283 (m), 2221 (m, CºN), 1648 (s), 1593 (s), 1546 (s), 1496 (s), 1447 (s), 1313 (m), 1231 (s), 893 (w), 752 (s), 695 (s) cm-1. MS: m/z (relative intensity) = 118 (43) [M+], 93 (97), 91 (42), 77 (25).
Compound 2f: 1H NMR (300 MHz, CDCl3): δ = 3.68 (br, 1 H, NH), 6.60 (d, 2 H, J = 8.52 Hz, ArH), 7.10 (d, 2 H, J = 8.51 Hz, ArH). 13C NMR (75 MHz, CDCl3): δ = 110.86, 116.63, 128.84, 129.72, 135.82. IR (diffuse reflectance): ν = 3374 (m), 2961 (m), 2232 (m, CºN), 1713 (m), 1600 (m), 1546 (s), 1495 (s), 1403 (m), 1283 (m), 1227 (m), 1092 (s), 821 (s), 639 (m) cm-1. MS: m/z (relative intensity) = 152 (100) [M+], 125 (49), 90 (27), 75 (23).
Compound 2g: 1H NMR (300 MHz, DMSO-d 6): δ = 5.36 (br, 1 H, NH), 6.51 (m, 1 H, ArH), 7.05 (m, 1 H, ArH), 7.25 (m, 1 H, ArH), 7.68 (m, 1 H, ArH). IR (diffuse reflectance): ν = 3192 (m), 2962 (m), 2229 (m, CºN), 1679 (s), 1597 (s), 1537 (s), 1481 (s), 1424 (m), 1224 (m), 1076 (m), 866 (m), 773 (m), 679 (m) cm-1.
Compound 2h: mp 178-180 °C. 1H NMR (300 MHz, CDCl3): δ = 4.32 (br, 1 H, NH), 6.60 (d, 2 H, J = 8.91 Hz, ArH), 8.06 (d, 2 H, J = 8.88 Hz, ArH). IR (diffuse reflectance): ν = 3360 (m), 2923 (m), 2221 (m, CºN), 1724 (m), 1630 (s), 1586 (s), 1504 (m), 1469 (s), 1444 (m), 1299 (s), 1113 (s), 999 (m), 839 (s) cm-1.
Compound 2i: 1H NMR (300 MHz, DMSO-d 6): δ = 5.79 (br, 1 H, NH), 6.93 (m, 1 H, ArH), 7.21-7.30 (m, 2 H, ArH), 7.36 (m, 1 H, ArH). 13C NMR (75 MHz, DMSO-d 6): δ = 107.39, 110.14, 120.35, 125.25, 130.32, 149.16, 150.52. IR (diffuse reflectance): ν = 3363 (m), 2964 (m), 2231 (m, CºN), 1721 (s), 1598 (m), 1530 (s), 1348 (s), 1224 (s), 1071 (m), 886 (m), 799 (m), 736 (m), 673 (m) cm-1.
Compound 2j: mp 76-78 °C. 1H NMR (300 MHz, CDCl3): δ = 1.75 (s, 3 H, CH3), 4.74 (br, 1 H, NH), 6.87-6.96 (m, 2 H, ArH), 7.13-7.33 (m, 2 H, ArH). IR (diffuse reflectance): ν = 3415 (m), 2925 (m), 2238 (m, CºN), 1702 (m), 1618 (w), 1589 (m), 1508 (s), 1456 (s), 1384 (m), 1231 (s), 1175 (m), 1066 (s), 1035 (s), 981 (m), 750 (s) cm-1.
Compound 2k: mp 65-67 °C. 1H NMR (300 MHz, CDCl3): δ = 4.20 (br, 1 H, NH), 3.87 (s, 3 H, OCH3), 6.86-6.91 (m, 1 H, ArH), 6.96-7.05 (m, 1 H, ArH), 7.28-7.39 (m, 2 H, ArH), 7.40-7.52 (m, 2 H, ArH), 7.55-7.61 (m, 2 H, ArH). 13C NMR (75 MHz, CDCl3): δ = 55.52, 110.57, 113.76, 117.15, 126.50, 126.70, 126.83, 128.53, 134.23, 136.25, 141.19, 146.95. IR (diffuse reflectance): ν = 3376 (m), 2938 (m), 2247 (w, CºN), 1952 (w), 1715 (m), 1602 (m), 1501 (s), 1248 (s), 1215 (m), 1180 (m), 1151 (m), 1048 (s), 1021 (s), 909 (m), 866 (m), 760 (s) cm-1. Anal. Calcd for C14H12N2O: C, 74.98; H, 5.39; N, 12.49%. Found: C, 74.96; H, 5.42; N, 12.46%.
Compound 2l: 1H NMR (300 MHz, CDCl3): δ = 2.09 (s, 3 H, CH3), 3.54 (br, 2 H, NH), 6.02-6.16 (m, 2 H, ArH), 6.88 (d, 1 H, J = 8.65 Hz, ArH). 13C NMR (75 MHz, CDCl3): δ = 102.79, 103.63, 105.74, 105.97, 112.80, 130.92, 145.20, 145.40. IR (diffuse reflectance): ν = 3352 (m), 2927 (m), 2219 (m, CºN), 1622 (s), 1515 (s), 1468 (m), 1321 (m), 1224 (m), 1066 (m), 998 (m), 846 (m), 800 (m), 454 (w) cm-1. Anal. Calcd for C9H8N4: C, 62.78; H, 4.68; N, 32.54%. Found: C, 62.76; H, 4.72; N, 32.52%.
Compound 2m: mp 155-157 °C. 1H NMR (300 MHz, CDCl3): δ = 6.63 (d, 4 H, J = 8.64 Hz, ArH), 6.80 (d, 4 H, J = 8.86 Hz, ArH). 13C NMR (75 MHz, CDCl3): δ = 115.26, 116.13, 119.41, 141.57, 150.50. IR (diffuse reflectance): ν = 3360 (m), 2952 (m), 2246 (m, CºN), 1865 (w), 1704 (m), 1629 (m), 1505 (m), 1216 (m), 1036 (m), 910 (m), 871 (m), 830 (m), 733 (m), 513 (m) cm-1.
Compound 4a: 1H NMR (300 MHz, acetone-d 6): δ = 2.94 (br, 1 H, NH), 4.80 (s, 2 H, CH2Cl). IR (diffuse reflectance): ν = 3376 (s, NH), 2958 (s), 2222 (m, CºN), 1682 (s, C=O), 1529 (m), 1402 (w), 1207 (w), 1045 (m), 917 (w), 768 (m) cm-1.
Compound 4b: mp 131-133 °C. 1H NMR (300 MHz, CDCl3): δ = 6.67 (br, 1 H, NH). 13C NMR (75 MHz, CDCl3): δ = 91.72, 128.33, 163.80. IR (diffuse reflectance): ν = 3371 (m), 3247 (m), 2221 (w, CºN), 1693 (s, C=O), 1610 (m), 1381 (m), 1352 (m), 1108 (m), 928 (w), 831 (s), 750 (m), 649 (m), 617 (m) cm-1. Anal. Calcd for C3HN2O: C, 19.23; H, 0.54; N, 14.95%. Found: C, 19.19; H, 0.53; N, 14.96%.
Compound 4c: mp 140-141 °C. 1H NMR (300 MHz, CDCl3): δ = 6.37 (br, 1 H, NH), 7.35-7.56 (m, 3 H, ArH), 7.81 (d, 2 H, J = 7.26 Hz, ArH). 13C NMR (75 MHz, CDCl3): δ = 127.25, 128.48, 128.70, 131.87, 133.26, 169.87. IR (diffuse reflectance): ν = 3371 (m), 3181 (m), 2918 (m), 2220 (m, CºN), 1657 (s, C=O), 1478 (m), 1392 (m), 1261 (m), 1195 (m), 1141 (s), 1119 (m), 807 (w), 789 (w) cm-1.