13
appearing as two doublet signals at 4.50 and 4.95 ppm (J = 1.5 Hz). The C NMR spectrum shows resonance
signals for carbon atoms at 88.94, 132.75, and 167.39 ppm which can be rationalized as due to the CH2= group,
the carbon atom at position 5 of the heterocycle, and the C=S bond respectively. This data is practically the same
as for the model structured 5-methylene-1,2,4-triazoline compounds which are the products of reaction of
thiosemicarbazide and its substituted analogs with 1,2-dicarbonyl compounds [12, 13]. The hydrazone 1 could
not be obtained in a pure state as attempts to separate it from the reaction mixture using TLC gave samples
containing both compound 1 and a certain amount of the methylene derivative 5. Formation of this latter
compound can be explained through conversion of monohydrazone 1 to the corresponding 5-hydroxy-
2H-[1,2,4]triazoline-3-thione and its subsequent dehydration.
Me
N
NR2
CNR2N
S
R2
RR1
RR1
NNH
NH2
MeC CMe
NNHCN
S
C(Me)COMe
+
–H2O
–H2O
H2C
S
N
N
O
O
1–3
RR1
5–10
R = R1 = R2 = H
MeC CMe
–H2O
O
O
HN
MeCOC(Me)
CN
NNH
C(Me)COMe
S
4
1–3, 5–7 R= H; 8, 9 R = Me; 1, 5 R1 = H; 2, 6 R1 = i-Pr; 3, 7 R1 = Ph; 8, 9 R1 = Me;
1–3, 5–8, 10 R2 = H; 9 R2 = Me; 10 R+R1 = МеСОС(Ме)=
It should be noted that hydrazone 1 presents as a single geometric isomer, evidently with a (Z)-configura-
tion relative to the C=N bond and allowing the formation of a chelating intramolecular hydrogen bond (IHB)
involving the NH and C=O bonds.
TABLE 1. 1H NMR Spectra of Compounds 1-10
Com-
pound
Chemical shifts, δ, ppm (J, Hz)*
1
2
3
4
5
6
1.94 (3Н, s, СН3C=N); 2.40 (3Н, s, СН3C=O); 4.85 (2H, s, NH2); 8.90 (1H, br. s, NHCS);
10.12 (1H, s, NHCS)
0.96 (6H, d, J = 5.9, CH(CH3)2); 1.98 (3Н, s, СН3C=N); 2.36 (3Н, s, СН3C=O);
3.2-3.6 (1H, m, CH(CH3)2); 5.05 (1H, br. s, NH); 8.50 (1Н, br. s, NHCS); 10.12 (1H, s, NHCS)
1.95 (3Н, s, СН3C=N); 2.40 (3Н, s, СН3C=O); 6.7-7.3 (5Н, m, C6H5); 7.90 (1H, s, NH);
8.75 (1Н, br. s, NHCS); 10.14 (1H, s, NHCS)
2.04 (6Н, s, СН3C=N); 2.25-2.55 (6H, br. s, CH3C=O); 10.10 (1H, s, NHCS);
10.52 (1H, s, NHCS)
2.03 (3Н, s, СН3C=N); 4.50 (1Н, d, J = 1.5, СН(Н)=C(5));
4.95 (1Н, d, J = 1.5, СН(Н)=C(5)); 5.10 (2H, s, NH2); 9.92 (1H, s, NHC=S)
0.98 (6H, d, J = 5.9, CH(CH3)2); 2.02 (3Н, s, СН3C=N); 3.2-3.6 (1H, m, CH(CH3)2);
4.45 (1Н, d, J = 0.9, СН(Н)=C(5)); 5.11 (1Н, d, J = 0.9, СН(Н)=C(5));
5.60 (1H, d, J = 6.0, NH); 9.85 (1H, s, NHC=S)
2.02 (3Н, s, СН3C=N); 4.50 (1Н, d, J = 0.8, СН(Н)=C(5)); 4.96 (1Н, d, J = 0.8, СН(Н)=C(5));
6.7-7.3 (5Н, m, C6H5); 7.40 (1H, s, NH); 9.62 (1H, s, NHC=S)
7
8
1.93 (3Н, s, СН3C=N); 2.95 (6Н, s, N(CH3)2); 4.40 (1Н, d, J = 1.0, СН(Н)=C(5));
5.08 (1Н, d, J = 1.0, СН(Н)=C(5)); 9.52 (1H, s, NHC=S)
9
1.98 (3Н, s, СН3C=N); 2.98 (6Н, s, N(CH3)2); 3.65 (3H, s, NCH3);
4.32 (1Н, d, J = 1.0, СН(Н)=C(5)); 4.92 (1Н, d, J = 1.0, СН(Н)=C(5))
10
1.86 (3Н, s, СН3C=N); 2.02 (3Н, s, СН3C=N); 2.55 (3Н, s, СН3C=O);
4.30 (1Н, d, J = 0.9, СН(Н)=C(5)); 4.46 (1Н, d, J = 0.9, СН(Н)=C(5)); 12.14 (1H, s, NHCS)
_______
Spectra recorded in CDCl3 (compounds 1-9) or DMSO-d6 (compound 10).
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