Catalyst-free synthesis of 1,5-benzodiazepines and 3.4-dihydroquinoxalines excluding DMAD^b.

Starting material	X	Product	R1	R2	R3	R4	Yield%
6a	O	10a	H	H	t-Bu	CH3	81
6g	S	10a	H	H	t-Bu	CH3	83
6h	N	10a	H	H	t-Bu	CH3	84
6a	O	10b	H	H	Tetramethylbutyl	CH3	77
6g	S	10b	H	H	Tetramethylbutyl	CH3	79
6h	N	10b	H	H	Tetramethylbutyl	CH3	80
6a	O	10c	H	H	Cyclohexyl	CH3	80
6g	S	10c	H	H	Cyclohexyl	CH3	82
6h	N	10c	H	H	Cyclohexyl	CH3	84
6h	N	10d	H	H	TosMe	CH3	71
6b	O	10e	CH3	CH3	t-Bu	CH3	74
6b	O	10f	CH3	CH3	Tetramethylbutyl	CH3	67
6d	O	11a	CO2CH3	H	t-Bu	CH3	46
6d	O	11b	CO2CH3	H	Tetramethylbutyl	CH3	52
6e	O	11ca	F	H	Tetramethylbutyl	CH3	30
6e	O	11da	H	F	Tetramethylbutyl	CH3	22
6f	O	11e	Cl	H	Tetramethylbutyl	CH3	46
6c	O	11f	Cl	Cl	t-Bu	CH3	74
6c	O	11g	Cl	Cl	Tetramethylbutyl	CH3	76
6h	N	11h	H	H	t-Bu	CH3CH2	76

^aCompounds 11c and 11d were isolated from the same reaction.

^bReaction conditions: isocyanide 2 (1 eq.), ketone 3 (2 eq.) and benzimidazole derivative 6 (1 eq.) were stirred at room temperature for 24 h.