Arkivoc 2019, ii, 0-0
Fesenko, A. A. et al.
(E)-2-Benzylsemicarbazone of benzaldehyde (2g). Compound 2g (0.979 g, 96%) as a white solid was obtained
from semicarbazone (E)-1d (0.657 g, 4.03 mmol), NaH (0.098 g, 4.08 mmol) and benzyl bromide (0.823 g, 4.81
mmol) in dry MeCN (13 mL) (rt, 19 h) as described for 2b. Mp 154-155 °C (EtOH) [Mp liter48 153-154 °C
(EtOH)]. IR (KBr) ν, cm–1: 3488 (s), 3349 (m), 3264 (br s), 3199 (br s), 3125 (br m) (ν NH), 3086 (w), 3027 (m) (ν
CHarom), 1693 (vs) (amide-I), 1601 (m) (ν C=N), 1575 (s) (δs NH2), 1494 (m) (ν CCarom), 757 (s), 734 (s), 692 (s) (δ
CHarom). 1H NMR (300.13 MHz, DMSO-d6) δ: 7.69-7.75 (2H, m, ArH), 7.59 (1H, s, CH=N), 7.19-7.38 (8H, m, ArH),
7.09 (1H, br s, NH), 6.85 (1H, br s, NH), 5.18 (2H, s, CH2). 13C NMR (75.48 MHz, DMSO-d6) δ: 156.8 (C=O), 137.0
(CH=N), 136.5 (C), 134.8 (C), 129.0 (CH), 128.6 (2CH), 128.5 (2CH), 126.9 (CH), 126.9 (2CH), 126.6 (2CH), 43.2
(CH2). Anal. Calcd for C15H15N3O: C, 71.13; H, 5.97; N, 16.59. Found: C, 70.87; H, 6.13; N, 16.47.
(E)-2-Benzylsemicarbazone of propanal (2h). Compound 2h (1.202 g, 70%) as a white solid was obtained from
semicarbazone 1e (0.962 g, 8.36 mmol) [a mixture of (E)- and (Z)-isomers in a ratio of 86:14, respectively], NaH
(0.221 g, 9.21 mmol) and benzyl bromide (1.575 g, 9.21 mmol) in dry MeCN (18 mL) (rt, 72 h) as described for
2b. Mp 92.5-94 °C (petroleum ether - AcOEt, 6:1 v/v). IR (KBr) ν, cm–1: 3485 (s), 3337 (m), 3267 (br s), 3208 (s),
3187 (s) (ν NH), 3084 (m), 3031 (m), 3005 (w) (ν CHarom), 1681 (vs) (amide-I), 1631 (s) (ν C=N), 1605 (w) (ν
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CCarom), 1562 (s) (δs NH2), 1525 (w), 1495 (m) (ν CCarom), 736 (s), 697 (s) (δ CHarom). H NMR (300.13 MHz,
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DMSO-d6) δ: 7.27-7.34 (2H, m, ArH), 7.18-7.25 (1H, m, ArH), 7.11-7.16 (2H, m, ArH), 6.85 (1H, t, J 4.8 Hz,
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CH=N), 6.61 (2H, br s, NH2), 4.98 (2H, s, NCH2), 2.14 (2H, dt, J 7.5, J 4.8 Hz, CH2 in Et), 0.92 (3H, t, J 7.5 Hz,
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CH3). C NMR (75.48 MHz, DMSO-d6) δ: 156.9 (C=O), 141.6 (CH=N), 136.6 (C), 128.4 (2CH), 126.7 (CH), 126.4
(2CH), 43.0 (NCH2), 25.4 (CH2 in Et), 10.7 (CH3). Anal. Calcd for C11H15N3O: C, 64.37; H, 7.37; N, 20.47. Found: C,
64.51; H, 7.57; N, 20.27.
(E)-2-Benzylsemicarbazone of butanal (2i). Compound 2i (2.588 g, 70%) as a white solid was obtained from
semicarbazone 1f (2.165 g, 16.76 mmol) [a mixture of (E)- and (Z)-isomers in a ratio of 74:26, respectively],
NaH (0.462 g, 19.25 mmol) and benzyl chloride (2.318 g, 18.31 mmol) in dry MeCN (35 mL) (reflux, 4 h) as
described for 2b. Mp 63.5-64 °C (petroleum ether - AcOEt, 15:1 v/v). IR (Nujol) ν, cm–1: 3484 (s), 3335 (m),
3266 (br s), 3209 (s), 3184 (s) (ν NH), 3084 (w), 3030 (m), 3002 (w) (ν CHarom), 1682 (amide-I), 1631 (m) (ν C=N),
1567 (s) (δs NH2), 1524 (w), 1495 (m) (ν CCarom), 742 (s), 699 (m) (δ CHarom). 1H NMR (300.13 MHz, DMSO-d6) δ:
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7.27-7.34 (2H, m, ArH), 7.17-7.24 (1H, m, ArH), 7.10-7.16 (2H, m, ArH), 6.80 (1H, t, J 5.3 Hz, CH=N), 6.60 (2H,
br s, NH2), 4.99 (2H, s, NCH2), 2.10 (2H, dt, 3J 7.3, 3J 5.3 Hz, CH2 in Pr), 1.35 (2H, qt, 3J 7.4, 3J 7.3 Hz, CH2 in Pr),
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0.74 (3H, t, J 7.4 Hz, CH3). C NMR (75.48 MHz, DMSO-d6) δ: 156.8 (C=O), 140.8 (CH=N), 136.5 (C), 128.4
(2CH), 126.7 (CH), 126.4 (2CH), 42.9 (NCH2), 34.0 (CH2), 19.6 (CH2), 13.2 (CH3). Anal. Calcd for C12H17N3O: C,
65.73; H, 7.81; N, 19.16. Found: C, 65.82; H, 7.81; N, 19.06.
(E)-2-(4-Methoxybenzyl)semicarbazone of butanal (2j). Compound 2j (2.734 g, 66%) as a white solid was
obtained from semicarbazone 1f (2.161 g, 16.73 mmol) [a mixture of (E)- and (Z)-isomers in a ratio of 74:26,
respectively], NaH (0.443 g, 18.46 mmol) and 4-methoxybenzyl chloride (2.879 g, 18.38 mmol) in dry MeCN
(25 mL) (reflux, 4 h) as described for 2b. Mp 89.5-90 °C (petroleum ether - AcOEt, 10:3 v/v). IR (KBr) ν, cm–1:
3490 (s), 3352 (m), 3268 (br s), 3188 (br s), 3140 (m) (ν NH), 3070 (w), 3036 (w) (ν CHarom), 1696 (vs) (amide-I),
1625 (m) (ν C=N), 1615 (m) (ν CCarom), 1581 (s) (δs NH2), 1513 (s) (ν CCarom), 1239 (s), 1036 (ν C-O), 801 (m) (δ
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CHarom). H NMR (300.13 MHz, DMSO-d6) δ: 7.04-7.10 (2H, m, ArH), 6.84-6.89 (2H, m, ArH), 6.83 (1H, t, J 5.3
Hz, CH=N), 6.56 (2H, br s, NH2), 4.91 (2H, s, NCH2), 3.71 (3H, s, OCH3), 2.10 (2H, dt, 3J 7.3, 3J 5.3 Hz, CH2 in Pr),
1.37 (2H, qt, 3J 7.4, 3J 7.3 Hz, CH2 in Pr), 0.76 (3H, t, 3J 7.4 Hz, CH3). 13C NMR (75.48 MHz, DMSO-d6) δ: 158.1 (C),
156.8 (C=O), 140.7 (CH=N), 128.3 (C), 127.7 (2CH), 113.9 (2CH), 55.0 (OCH3), 42.3 (NCH2), 34.0 (CH2), 19.6
(CH2), 13.2 (CH3). Anal. Calcd for C13H19N3O2: C, 62.63; H, 7.68; N, 16.85. Found: C, 62.71; H, 7.71; N, 16.75.
(E)-2-Benzylsemicarbazone of 2-methylpropanal (2k). Compound 2k (3.936 g, 72%) as a white solid was
obtained from semicarbazone (E)-1g (3.236 g, 25.05 mmol), NaH (0.691 g, 28.79 mmol) and benzyl chloride
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