Table 1.

Results for the screening of the reaction conditions^a.

entry	compound 3	X, R1, R2, R3	conditions	ratio of 4 and 5	total yield of 4 + 5 [%]	yield of 4 [%]b
1	3a	X = O, R1 = R2 = Me, R3 = H	MeOH, reflux, 2 h	38:62	80	–c
2			95% EtOH, reflux, 2 h	30:70	72	–c
3			Anh. EtOH, reflux, 2 h	32:68	71	–c
4			AcOH, 50 °C, 2 h	83:17	72	–c
5			AcOH, 40 °C, 2 h	84:16	79	45
6			AcOH, 20 °C, 2 h	91:9	80	53
7	3b	X = O, R1 = R2 = Et, R3 = H	MeOH, reflux, 2 h	54:46	68	–c
8			AcOH, 20 °C, 2 h	66:34	71	47
9	3c	X = O, R1 = R2 = Me, R3 = Ph	MeOH, reflux, 2 h	97:3	81	79
10			95% EtOH, reflux, 2 h	100:0	68	68
11	3d	X = O, R1 = Me, R2 = Ph, R3 = H	MeOH, reflux, 2 h	77:23	48	–c
12			AcOH, 20 °C, 2 h	100:0	64	64d
13			AcOH, 20 °C, 4 h	100:0	86	86
14	3f	X = S, R1 = Me, R2 = Ph, R3 = H	MeOH, reflux, 4 h	100:0	52	52
15			AcOH, 20 °C, 4 h	–	0	0

^aReaction conditions: stirring the mixture of imidazo[4,5-e][1,2,4]triazin-3-thione 3 (2.0 mmol) and DEAD (2.1 mmol) in solvent (4 mL). ^bIsolated yield. ^cPure product 4 was not isolated. ^dProduct 4k was isolated as a mixture with 3d.