Table 2.

Et₃N-catalyzed synthesis of 2,3,6,7,9-pentaazabicyclo[3.3.1]nona-3,7-dienes 2a–p.

Run	Products	R	Ar	Conv. Heating a		Sonication a		MW a Irradiation
				Yield b%	Time (h)	Yield b %	Time (min)	Yield b %	Time (min)
1	2a	4-FC6H4	4-ClC6H4	78	3	89	50	94	3
2	2b	4-FC6H4	4-BrC6H4	77	4	87	60	93	4
3	2c	C6H5	4-ClC6H4	70	3	81	50	89	4
4	2d	C6H5	4-BrC6H4	72	5	82	70	90	6
5	2e	C6H5	2-NO2C6H4	68	4	80	70	86	5
6	2f	4-ClC6H4	C6H5	71	3	83	40	90	3
7	2g	4-ClC6H4	4-BrC6H4	73	5	84	70	91	5
8	2h	4-BrC6H4	4-ClC6H4	86	4	87	70	92	5
9	2i	4-BrC6H4	4-BrC6H4	84	5	86	80	92	6
10	2j	4-OMeC6H4	C6H5	66	5	77	70	82	5
11	2k	4-OMeC6H4	4-ClC6H4	65	6	77	90	81	6
12	2l	4-OMeC6H4	4-BrC6H4	67	8	78	100	83	7
13	2m	4-NO2C6H4	4-ClC6H4	67	7	79	110	84	7
14	2n	4-NO2C6H4	4-BrC6H4	71	8	80	100	86	8
15	2o	CH3	4-ClC6H4	62	7	73	90	81	8
16	2p	CH3	4-BrC6H4	64	6	75	110	81	9

^a Reaction conditions: 3-Oxo-2-arylhydrazonopropanals 1a–p (5 mmol), ammonium acetate (10 mmol) and Et₃N (25 mol%) in EtOH (7 mL) at reflux temperature for conventional heating 3~8 h, ultrasonic irradiation at 80 °C (110 W) for 50~110 min, or microwave irradiation at 80 °C (200 W) for 3~9 min. ^b Isolated yields. Conv. = conventional, MW = microwave.