General procedure for the synthesis of enaminones
77 (97). HRMS (EI) m=z: calcd for C21H18N2O: 314.1419,
found 314.1426.z
To a stirred solution of a boron complex (1 equiv.) in aceto-
nitrile (8 mL), amine (3 equiv.) was added at room tempera-
ture. In the case of ammonia or methylamine, the amine was
passed over the stirred solution of a boron complex for 5 min
at room temperature. The reaction mixture was stirred at room
temperature for 0.25–1.5 h (see Table 2) and then evaporated
to dryness. The residue was dissolved in dichloromethane
(30 mL), washed with water (2 ꢁ 10 mL), dried over magne-
sium sulfate and evaporated to dryness. Products were purified
in some cases byflash chromatography.
(2Z)-2-(1-Aminoethylidene)-3,4-dihydro-1(2H)-naphthalenone
(4a). IR (KBr, n cmÀ1): 3289, 2888, 2831, 1591, 1487, 1359,
1308, 1146, 1032, 986, 901, 847, 777, 743. 1H NMR (300
MHz, CDCl3): d 2.07 (s, 3H), 2.60 (t, 2H, J¼7.2 Hz), 2.84
(t, 2H, J¼7.2 Hz), 5.10 (br s, 1H), 7.15–7.37 (m, 3H), 7.99–
8.02 (m, 1H), 10.88 (br s, 1H). 13C NMR (75 MHz, CDCl3):
d 21.6, 25.0, 29.6, 101.3, 126.9 (2C), 127.6, 131.3, 136.2,
142.0, 160.7, 186.1. MS (EI, 70 eV) m=z (%) 187 (Mþ, 100),
172 (14), 97 (13), 69 (15). HRMS (EI) m=z calcd for
C12H13NO: 187.0997, found 187.1005.
(2Z)-1-Phenyl-3-[(2-sulfanylethyl)amino]-2-buten-1-one (2d).
Colourless oil. IR (NaCl plates, n cmÀ1): 3058, 2930, 2554,
1598, 1545, 1438, 1373, 1321, 1291, 1177, 1087, 1065, 1027,
(2Z)-2-[1-(Methylamino)ethylidene]-3,4-dihydro-1(2H)-
naphthalenone (4b). IR (KBr, n cmÀ1): 2929, 2830, 1594, 1547,
1476, 1318, 1252, 1182, 1062, 899, 785, 743. 1H NMR (300
MHz, CDCl3): d 2.02, (s, 3H), 2.57 (t, 2H, J¼6.4 Hz), 2.80
(t, 2H, J¼6.4 Hz), 2.98 (d, 3H, J¼5.1 Hz), 7.12–7.15
(m, 1H), 7.25–7.32 (m, 2H), 7.97–8.01 (m, 1H), 12.52 (br s,
1H). 13C NMR (75 MHz, CDCl3): d 14.63, 25.0, 29.6, 30.2,
100.5, 126.3, 126.7, 127.2, 130.5, 136.5, 141.1, 164.7, 183.3.
MS (EI, 70 eV) m=z (%) 201 (Mþ, 100), 186 (52), 56 (97).
HRMS (EI) m=z calcd for C13H15NO: 201.1154, found
201.1160.
1
739. H NMR (300 MHz, CDCl3): d 1.60 (t, 1H, J¼8.5 Hz),
2.07 (s, 3H), 2.67–2.74 (m, 2H), 3.46–3.52 (m, 2H), 5.69
(s, 1H), 7.34–7.42 (m, 3H), 7.83–7.86 (m, 2H), 11.55 (br s,
1H). 13C NMR (75 MHz, CDCl3): d 19.4, 25.0, 46.2, 92.6,
126.8, 128.1, 130.5, 140.1, 164.4, 187.9. MS (EI, 70 eV) m=z
(%) 221 (Mþ, 42), 188 (69), 174 (76), 105 (100), 91 (77), 77
(67). HRMS (EI) m=z calcd for C12H15NOS: 221.0874, found
221.0882.
(2Z)-1-Phenyl-3-[(3-pyridinylmethyl)amino]-2-buten-1-one
(2e). The colourless oil obtained on work-up was subjected to
flash chromatography(5 : 3 petroleum ether–ethly acetate
elution). IR (NaCl plates, n cmÀ1): 3058, 1601, 1543, 1435,
1319, 1295, 1065, 742. 1H NMR (300 MHz, CDCl3): d 1.95
(s, 3H), 4.54 (d, 2H, J¼6.4 Hz), 5.69 (s, 1H), 7.04–7.32 (m,
5H), 7.50–7.56 (m, 1H), 7.80–7.84 (m, 2H), 8.48 (d, 1H,
J¼3.4 Hz), 11.80 (br s, 1H). 13C NMR (75 MHz, CDCl3): d
19.6, 48.6, 92.9, 121.1, 122.5, 127.0, 128.2, 130.6, 137.1,
140.3, 149.5, 157.2, 164.9, 188.1. MS (EI, 70 eV) m=z (%)
252 (Mþ, 37), 147 (100), 133 (72), 105 (52), 92 (50), 77 (55).
(2Z)-2-[1-(Isopropylamino)ethylidene]-3,4-dihydro-1(2H)-
naphthalenone (4c). Colourless oil. IR (NaCl plates, n cmÀ1):
2970, 2930, 1591, 1553, 1469, 1314, 1254, 1156, 1119, 743.
1H NMR (300 MHz, CDCl3): d 1.30 (d, 6H, J¼6.1 Hz), 2.06
(s, 3H), 2.56 (t, 2H, J¼7.6 Hz), 2.80 (t, 2H, J¼7.6 Hz),
3.75–3.86 (m, 1H), 7.12–7.32 (m, 3H), 8.00–8.10 (m, 1H),
12.74 (br s, 1H). 13C NMR (75 MHz, CDCl3): d 14.8, 24.1,
24.8, 29.5, 45.2, 100.1, 126.2, 126.6, 127.1, 130.4, 136.5,
140.9, 162.6, 183.0. MS (EI, 70 eV) m=z (%) 229 (Mþ, 100),
212 (70), 186 (86), 145 (40), 69 (85). HRMS (EI) m=z calcd
for C15H19NO: 229.1467, found 229.1475.
(2Z)-3-[(2-Hydroxy-1,1-dimethylethyl)amino]-1-phenyl-2-
buten-1-one (2f ). Colourless oil. IR (NaCl plates, n cmÀ1):
3367, 2972, 2931, 1596, 1549, 1338, 1067, 740. H NMR (300
1
(2Z)-2-{1-[(2-Sulfanylethyl)amino]ethylidene}-3,4-dihydro-
1(2H)-naphthalenone (4d). Yellow oil. IR (NaCl plates,
n cmÀ1): 2930, 2834, 2556, 1589, 1466, 1319, 1252, 1173,
1065, 744. 1H NMR (300 MHz, CDCl3): d 1.60 (t, 1H,
J¼6.5 Hz), 2.02 (s, 3H), 2.56 (t, 2H, J¼7.8 Hz), 2.67–2.81
(m, 4H), 3.49 (t, 2H, J¼6.5 Hz), 7.11–7.14 (m, 1H), 7.26–
7.30 (m, 2H), 7.97–8.00 (m, 1H), 12.70 (br s, 1H). 13C NMR
(75 MHz, CDCl3): d 14.4, 24.4, 24.7, 28.9, 46.3, 100.5, 125.9,
126.1, 126.7, 130.2, 135.7, 140.6, 162.4, 183.5. MS (EI, 70
eV) m=z (%) 247 (Mþ, 46), 214 (58), 200 (100), 102 (49).
HRMS (EI) m=z calcd for C14H17NOS: 247.1031, found
247.1037.
MHz, CDCl3): d 1.40 (s, 6H), 2.13 (s, 3H), 3.61 (s, 2H), 3.83
(br s, 1H), 5.57 (s, 1H), 7.35–7.40 (m, 3H), 7.80–7.84
(m, 2H), 11.90 (br s, 1H). MS (EI, 70 eV) m=z (%) 233 (Mþ,
18), 202 (100), 184 (25), 162 (27), 105 (37). HRMS (EI) m=z
calcd for C14H19NO2 : 233.1416, found 233.1424.
(2Z)-1,3-Diphenyl-3-[(2-sulfanylethyl)amino]-2-propen-1-one
(3b). Colourless oil. IR (NaCl plates, n cmÀ1): 3058, 1594,
1566, 1480, 1331, 1058, 750. NMR (300 MHz, CDCl3): d
1.49 (t, 1H, J¼8.5 Hz), 2.59–2.67 (m, 2H), 3.37–3.44 (m,
2H), 5.80 (s, 1H), 7.38–7.46 (m, 8H), 7.88–7.91 (m, 2H),
11.45 (br s, 1H). 13C NMR (75 MHz, CDCl3): d 25.6, 47.7,
94.2, 127.2, 127.8, 128.3, 128.7, 129.7, 130.9, 135.5, 140.2,
166.6, 188.9. MS (EI, 70 eV) m=z (%) 283 (Mþ, 27), 250
(100), 236 (82), 105 (36). HRMS (EI) m=z calcd for
C17H17NOS: 283.1031, found 283.1041.
(2Z)-2-{1-[(3-Pyridinylmethyl)amino]ethylidene}-3,4-dihydro-
1(2H)-naphthalenone (4e). IR (KBr, n cmÀ1): 2989, 1586, 1545,
1466, 1423, 1366, 1310, 1287, 1248, 1173, 1063, 1016, 815, 733,
1
710. H NMR (300 MHz, CDCl3): d 2.05 (s, 3H), 2.61 (t, 2H,
J¼6.3 Hz), 2.83 (t, 2H, J¼6.3 Hz), 4.56 (d, 2H, J¼6.0 Hz),
7.14–7.36 (m, 4H), 7.65–7.68 (m, 1H), 7.97–8.00 (m, 1H),
8.52–8.57 (m, 2H), 12.88 (br s, 1H). 13C NMR (75 MHz,
CDCl3): d 14.9, 24.8, 29.3, 44.9, 101.5, 123.8, 126.3, 126.6,
127.1, 130.8, 133.9, 134.7, 135.9, 144.1, 148.7, 149.0, 162.6,
184.5. MS (EI, 70 eV) m=z (%) 278 (Mþ, 87), 261 (70), 186
(77), 92 (100), 65 (54). HRMS (EI) m=z calcd for
C18H18N2O: 278.1419, found 278.1420.
(2Z)-1,3-Diphenyl-3-[(3-pyridinylmethyl)amino]-2-propen-1-
one (3c). The colourless oil obtained on work-up was
subjected to flash chromatography(5 : 3 petroleum ether–
ethyl acetate elution). IR (NaCl plates, n cmÀ1): 3059, 2927,
1593, 1566, 1480, 1331, 1226, 1057, 1025, 752. 1H NMR
(300 MHz, CDCl3): d 4.38 (d, 2H, J¼6.6 Hz), 5.87 (s, 1H),
7.18–7.22 (m, 1H), 7.33–7.53 (m, 8H), 7.53–7.57 (m, 1H),
7.87–7.90 (m, 2H), 8.36 (d, 1H, J¼1.8 Hz), 8.46–8.49
(m, 1H), 11.68 (br s, 1H). 13C NMR (75 MHz, CDCl3): d
45.9, 94.5, 123.6, 127.1, 127.7, 128.3, 128.7, 129.8, 131.0,
134.1, 134.7, 135.1, 139.9, 148.6, 148.8, 166.6, 189.0. MS (EI,
2-[(Z)-1-Aminoethylidene]-1-cyclopentanone (5a). IR (KBr,
n cmÀ1): 3304, 3156, 2956, 2914, 1627, 1509, 1256, 1045, 913,
633. 1H NMR (300 MHz, CDCl3):
d 1.85 (dd, 2H,
30
New J. Chem., 2002, 26, 28–32