Arylhydrazononitriles as precursors to 2-substituted 1,2,3-triazoles and 4-amino-5-cyano-pyrazole derivatives utilizing microwave and ultrasound irradiation

Figures & data

Scheme 1.  Synthesis of cyanoacetamides

Figure 1.  X-ray crystal structure of 4c.

Scheme 2.  Synthesis of 2-arylhydrazononitrile derivatives.

Scheme 3.  Synthesis of 5-amino-1,2,3-triazole and 1,2,3-triazolo[4,5-d]pyrimidin-7-one derivatives

Scheme 4.  Synthesis of pyrazole derivatives.

Table 1. Yield as well as reaction times by the three methodologies are compared.

No.	Time			Yield%
	Δ	Mw	Us	Δ	Mw	Us
3a	3 h	4 min	7 min	67	89	74
3b	4 h	3 min	10 min	90	91	88
3c	2 h	2 min	5 min	83	90	80
3d	1 h	1 min	2 min	89	93	90
5a	1 h	2 min	30 min	40	80	72
5b	1 h	5 min	30 min	37	74	70
5c	1 h	4 min	30 min	48	80	76
5d	1 h	3 min	30 min	35	35	66
5e	1 h	2 min	30 min	40	75	78
5f	1 h	3 min	30 min	44	89	81
5g	1 h	5 min	30 min	48	80	77
5h	1 h	3 min	30 min	39	79	78
7a	1 h	2 min	1 h	40	60	58
7b	1 h	2 min	1 h	44	73	70
7c	1 h	3 min	1 h	45	77	68
7d	1 h	2 min	1 h	43	79	71
7e	1 h	4 min	1 h	40	66	56
10a	7 h	2 min	–	47	90	–
10b	7 h	2 min	–	46	88	–
13a	1 h	2 min	1 h	60	77	73
13b	1 h	2 min	1 h	55	84	78
13c	1 h	2 min	1 h	59	79	70
13d	1 h	2 min	1 h	58	89	84
13e	1 h	2 min	1 h	54	80	78

Table 2. Crystal data of compound 4c.

Chemical formula	C17H20N4O3
M	328.372
System	Monoclinic
Space group	P21/c
a	9.9877 (6) Å
b	18.0058 (8) Å
c	9.8843 (4) Å
α	90.00°
β	96.078 (2)°
V	1767.6 (2) Å^3
Z	4
Dc	1.234 mg m^−3
κ	2.910–24.713°
µ(Mo–Kα)	0.09 mm^−1
T	298 K
Measured reflections	4990
Independent reflections	3497
Observed reflections	1335
R int	0.031
R(all)	0.140
WR(ref)	0.184
WR(all)	0.238
S(ref)	1.429
S(all)	1.364
D/smax	0.027
Drmax	0.38e Å^3
Drmin	−0.41e Å^3