Table 1.

Synthesis of N-substituted 4-aminopyrrolo[3,2-c]quinolines 22 by electrocyclization of carbodiimides 20.

entry	R		19		20		22
			time (h)	yield (%)	time (h)	yield (%)	time (h)	yield (%)
1		a	12	50	4	64	2	90
2		b	12	98	1	–a	2	49b
3		c	20	64	2	75	1	61
4		d	18	98	0.5	68	1	–c

^aSince carbodiimide 20b was unstable, the next reaction was carried out without purification. ^bYield from 19b. ^cUnknown compounds.