Synlett 2009(5): 818-822  
DOI: 10.1055/s-0028-1087914
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Solid-State Synthesis of β-Enamino Ketones from Solid 1,3-Dicarbonyl Compounds and Ammonium Salts or Amines

Shi-Liang Xua, Cheng-Ping Lib, Jing-Hua Li*a
a College of Pharmacuetical Sciences, Zhejiang University of Technology, 310032 Hangzhou, P. R. of China
b College of of Biology and Environmental Engineering, Zhejiang Shuren University, 310015 Hangzhou, P. R. of China
e-Mail: lijh@zjut.edu.cn;
Further Information

Publication History

Received 16 October 2008
Publication Date:
16 February 2009 (online)

Abstract

A facile amination of solid 1,3-dicarbonyl compounds with ammonium salts or amines in solid state has been achieved by mechanochemical grinding in the presence of KHSO4 and SiO2. Most of the reactions proceed smoothly at room temperature under solid-state conditions and give their corresponding β-imino derivatives in high yields. The method has the advantage of simple manipulation and mild conditions.

32

General Procedure for the Preparation of β-Enamino Ketones
A mixture of the solid 1,3-dicarbonyl compound (5 mmol), amine (or ammonium, 5 mmol), and KHSO4/SiO2 (0.136 g, weight ratio 1:1) was ground in a mortar at r.t. for the appropriate time. After completion of the reaction as indicated by TLC, the reaction mixture was extracted with CH2Cl2 (2 × 10 mL). The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure to give a product with high purity. The solid product could be further purified by recrystallization in PE (Table  [²] , entries 1-15) or in EtOH (Table  [³] , entries 1-12).
3-Amino-1-phenylbut-2-en-1-one (2a)
Mp 138-140 ˚C; lit. [³³a] 144-145 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.06 (s, 3 H), 5.21 (br, 1 H, NH), 5.74 (s, 1 H), 7.39-7.45 (m, 3 H), 7.87-7.89 (m, 2 H), 10.22 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 22.92, 92.34, 127.10, 128.22, 130.83, 140.20, 162.91, 189.54.
3-Amino-1-(4-methoxyphenyl)but-2-en-1-one (2b) [³³b]
Mp 106-108 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.04 (s, 3 H), 3.85 (s, 3 H), 5.11 (br, 1 H,NH), 5.70 (s, 1 H), 6.89-6.92 (m, 2 H), 7.85-7.88 (m, 2 H), 10.13 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 22.95, 55.36, 91.88, 113.43, 129.03, 132.90, 161.89, 162.14, 188.65.
3-Amino-1-(4-fluorophenyl)but-2-en-1-one (2c) [³³b]
Mp 106-108 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.06 (s, 3 H), 5.21 (br, 1 H, NH), 5.67 (s, 1 H), 7.06-7.09 (m, 2 H), 7.87-7.90 (m, 2 H), 10.19 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3) δ = 22.95 91.99, 115.14 (d, J = 20 Hz), 129.39 (d, J = 9 Hz), 136.40, 136.42 163.30 (d, J = 56 Hz), 165.52, 188.08. Ethyl 2-Amino-4-oxo-4-phenylbut-2-enoate (2d)
Mp 49-51 ˚C; lit. [³³c] 50-51 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 1.41 (t, 3 H, J = 7 Hz), 4.38 (q, 2 H, J = 7 Hz), 6.04 (br, 1 H, NH), 6.67 (s, 1 H), 7.46-7.54 (m, 3 H), 7.96-9.98 (m, 2 H), 9.49 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 14.13, 62.70, 93.26, 127.45, 128.44, 131.29, 139.28, 147.49, 163.88, 191.80.
3-Aminocyclohex-2-enone (2e)
Mp 128-130 ˚C; lit. [³³d] 133 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 1.97 (m, 2H), 2.29 (t, 2H, J = 6 Hz), 2.35 (t, 2H, J = 6 Hz), 4.67 (br, 2H, NH), 5.26 (s, 1H). ¹³C NMR (125 MHz, D2O) δ = 23.89, 30.60, 36.94, 99.56, 177.00, 203.01.
3-Amino-5,5-dimethylcyclohex-2-enone (2f)
Mp 164-166 ˚C; lit. [³³d] 165-167 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 1.08 (s, 6 H), 2.16 (s, 2 H), 2.20 (s, 2 H), 4.71 (br, 2 H, NH), 5.25 (s, 1 H). ¹³C NMR (125 MHz, D2O) δ = 28.35, 32.88, 42.65, 49.86, 99.27, 163.46, 197.31.
3-Amino-1,3-diphenylprop-2-en-1-one (2g) [³³e]
Mp 78-79 ˚C. ¹H NMR (500 MHz, CDCl3) δ = 5.46 (br, 1 H, NH), 6.16 (s, 1 H), 7.42-7.53 (m, 6 H), 7.64-7.65 (m, 2 H), 7.94-7.96 (m, 2 H), 10.43 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3) δ = 91.93, 126.36, 127.24, 128.32, 129.06, 130.74, 131.06, 137.63, 140.36, 162.88, 190.26.
3-Amino-1-(thiophen-2-yl)but-2-en-1-one (2h)
Mp 168-170 ˚C; lit. [³³b] 168-170 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.03 (s, 3 H), 5.31 (br, 1 H,NH), 5.60 (s, 1 H), 7.05-7.56 (m, 3 H), 9.91 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 22.73, 92.00, 127.73, 127.87, 130.21, 146.99, 162.82, 182.21.
3-(4-Methoxyphenylamino)-1-phenylbut-2-en-1-one (3a) [³³f]
Mp 100-102 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.07 (s, 3 H), 3.82 (s, 3 H), 5.86 (s, 1 H), 6.89-6.91 (m, 2 H), 7.10-7.12 (m, 2 H), 7.41-7.46 (m, 3 H), 7.90-7.92 (m, 2 H), 12.92 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 20.27, 55.52, 93.59, 114.37, 126.64, 127.05, 128.28, 130.80, 131.46, 140.16, 157.89, 163.21, 188.47.
3-(4-Chlorophenylamino)-1-phenylbut-2-en-1-one (3b)
Mp 126-128 ˚C; lit. [³³g] 128-129 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.12 (s, 3 H), 5.91 (s, 1 H), 7.09-7.15 (m, 2 H), 7.31-7.34 (m, 2 H), 7.41-7.48 (m, 3 H), 7.90-7.92 (m, 2 H), 13.07 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 20.30, 94.63, 125.80, 127.01, 128.26, 129.23, 131.02, 131.15, 137.20, 139.71, 161.63, 188.88.
3-(4-Nitrophenylamino)-1-phenylbut-2-en-1-one (3c) [³³h]
Mp 140-142 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.33 (s,
3 H), 6.04 (s, 1 H), 7.25-7.28 (m, 2 H), 7.44-7.47 (m, 2 H), 7.50-7.52 (m, 1 H), 7.88-7.93 (m, 2 H), 8.21-8.25 (m, 2 H), 13.41 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 21.18, 97.54, 122.26, 125.22, 127.30, 128.50, 131.73, 139.20, 144.13, 145.18, 159.16, 189.99.
1-Phenyl-3-( p -tolylamino)but-2-en-1-one (3d) [³³i]
Mp 114-116 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.10 (s,
3 H), 2.35 (s, 3 H), 5.87 (s, 1 H), 7.05-7.07 (m, 2 H), 7.15-7.25 (m, 2 H), 7.40-7.46 (m, 3 H), 7.90-7.93 (m, 2 H), 13.03 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 20.38, 20.97, 93.92, 124.85, 127.06, 128.27, 129.76, 130.82, 135.72, 136.02, 140.14, 162.60, 188.48.
1-(4-Methoxyphenyl)-3-(4-methoxyphenylamino)but-2-en-1-one (3e) [³³j]
Mp 142-143 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.05 (s, 3 H), 3.82 (s, 3 H), 3.86 (s, 3 H), 5.82 (s, 1 H), 6.88-6.94 (m, 4 H), 7.09-7.11 (m, 2 H), 7.89-7.91 (m, 2 H), 12.85 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 20.26, 55.36, 55.49, 93.05, 113.47, 114.31, 126.57, 128.90, 131.67, 132.81, 157.74, 161.87, 162.41, 187.62. 1-(4-Fluorophenyl)-3-(4-methoxyphenylamino)but-2-en-1-one (3f)
Mp 116-118 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.06 (s, 3 H), 3.82 (s, 3 H), 5.80 (s, 1 H), 6.89-6.91 (m, 2 H), 7.07-7.11 (m, 4 H), 7.90-7.93 (m, 2 H), 12.87 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 20.25, 55.49, 93.15, 114.37, 115.16 (d, J = 21 Hz), 126.63, 129.24 (d, J = 9 Hz), 131.35, 136.36 (d, J = 4 Hz), 157.94, 163.38 (d, J = 22 Hz), 165.47, 186.94. IR (KBr): 3440, 1599, 1543, 1515, 1496, 1462, 1436, 1328, 1251, 1198, 1105, 1031, 855, 779, 520 cm. MS (EI): m/z (%) = 286 (18), 285 (100) [M+], 284 (70), 270 (18), 190 (11), 162 (36), 147 (22), 123 (71), 108 (9), 95 (27). Anal. Calcd for C17H16FNO2: C, 71.56; H, 5.65; N, 4.91. Found: C, 71.51; H, 5.60; N, 4.87.
Ethyl 2-(4-Nitrophenylamino)-4-oxo-4-phenylbut-2-enoate (3g)
Mp 98-99 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 1.22 (t, 3 H, J = 7 Hz), 4.28 (q, 2 H, J = 7 Hz), 6.67 (s, 1 H), 7.04-7.05 (m, 2 H), 7.47-7.51 (m, 2 H), 7.57-7.60 (m, 1 H), 7.97-7.99 (m, 2 H), 8.19-8.21 (m, 2 H), 11.95 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 13.83, 62.79, 101.02, 120.30, 125.09, 127.77, 128.76, 132.95, 138.10, 143.72, 145.72, 146.95, 163.64, 191.94. IR (KBr): 3441, 2981, 1373, 1619, 1585, 1510, 1337, 1281, 1226, 1163, 1108, 1051, 1016, 831, 853, 750, 591, 552, 493 cm. MS (EI): m/z (%) = 341 (5), 340 (33) [M+], 339 (31), 294 (14), 268 (18), 267 (84), 236 (26), 221 (15), 105 (100), 77 (42). Anal. Calcd for C18H16N2O5: C, 63.52; H, 4.74; N, 8.23. Found: C, 63.50; H, 4.67; N, 8.14.
3-(4-Nitrophenylamino)cyclohex-2-enone (3h) [³³k]
Mp 176-178 ˚C.¹H NMR (500 MHz, CDCl3): δ = 2.07-2.11 (m, 2 H), 2.42 (t, 2 H, J = 7 Hz), 2.56 (t, 2 H, J = 6 Hz), 5.85 (s, 1 H), 6.83 (br, 1 H, NH), 7.26-7.29 (m, 2 H), 8.19-8.21 (m, 2 H). ¹³C NMR (125 MHz, CDCl3): δ = 21.65, 29.82, 36.55, 103.13, 121.31, 125.32, 143.35, 144.94, 159.90, 198.94.
3-(4-Methoxyphenylamino)-5,5-dimethylcyclohex-2-enone (3i)
Mp 186-188 ˚C; lit. [³³l] 186-188 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 1.05 (s, 6 H), 2.15 (s, 2 H), 2.32 (s, 2 H), 3.78 (s, 3 H), 5.34 (s, 1 H), 6.82 (dd, 2 H, J = 2, 7 Hz), 7.04 (dd, 2 H, J = 2, 7 Hz), 7.28 (s, 1 H).¹³C NMR (125 MHz, CDCl3): δ = 28.27, 32.76, 43.02, 50.36, 55.46, 96.96, 114.37, 126.07, 131.14, 157.46, 162.87, 197.61.
3-(2,5-Dichlorophenylamino)-5,5-dimethylcyclohex-2-enone (3j)
Mp 182-184 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 1.14 (s, 6 H), 2.26 (s, 2 H), 2.39 (s, 2 H), 5.61 (s, 1 H), 6.12 (br, 1 H), 7.07-7.42 (m, 3 H). ¹³C NMR (125 MHz, CDCl3): δ = 28.28, 32.89, 43.74, 50.34, 100.78, 124.56, 125.27, 125.96, 130.79, 133.30, 136.28, 158.05, 198.18. IR (KBr) 3442, 3225, 2953, 2873, 1597, 1537, 1464, 1402, 1364, 1269, 1092, 1048, 925, 893, 827, 743, 519 cm. MS (EI): m/z (%) = 285 (42), 283 (50), 268 (20), 266 (20), 227 (36), 192 (100), 164 (28). Anal. Calcd for C14H15Cl2NO: C, 59.17; H, 5.32; N, 4.93. Found: C, 59.09; H, 5.28; N, 4.90.
1,3-Diphenyl-3-( p -tolylamino)prop-2-en-1-one (3k) [³³m]
Mp 120-122 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.23 (s, 3 H), 6.05 (s, 1 H), 6.68-7.95 (m, 14 H), 12.90 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 20.79, 96.57, 123.21, 127.22, 128.33, 128.38, 128.49, 129.31, 129.55, 131.17, 133.86, 135.94, 136.80, 139.98, 161.74, 189.43.
3-(4-Chlorophenylamino)-1-(thiophen-2-yl)but-2-en-1-one (3l)
Mp 80-82 ˚C. ¹H NMR (500 MHz, CDCl3): δ = 2.11 (s, 3 H), 5.78 (s, 1 H), 7.06-7.61 (m, 7 H), 12.71 (br, 1 H, NH). ¹³C NMR (125 MHz, CDCl3): δ = 20.31, 94.51, 125.74, 127.89, 128.14, 129.34, 130.66, 131.21, 137.24, 146.56, 161.33, 181.88. IR (KBr): 3441, 3095, 1623, 1562, 1481, 1418, 1373, 1381, 1229, 1093, 1031, 824, 834, 766, 722, 502
cm. MS (EI): m/z (%) = 279 (25), 278 (39), 277 (67), 276 (84), 244 (87), 111 (100), 83 (8). Anal. Calcd for C14H12ClNOS: C, 60.54; H, 4.35; N, 5.04. Found: C, 60.50; H, 4.31; N, 5.01.