Table 5. Synthesis of pyrimido[4,5-b]quinoline derivatives in the presence of the catalyst.

Entry	Product	Time (min)	Yielda (%)	M.p. °C (Lit.)
1		15	89	244–245 (253–255)17
2		10	81	346–350 (—)
3		12	89	247–249 (238–240)37
4		10	95	347–351 (350–355)17
5		19	85	293–296 (>300)24
6		24	79	346–349 (—)
7		25	78	289–293 (285–287)24
8		30	85	296–298 (>300)
9		10	85	288–289 (292–294)24
10		40	83	298–301 (300–303)17
11		10	97	225–229 (226–229)35
12		35	95	315–320 (>300)24
13		20	93	278–282 (301–303)35
14		25	99	310–314 (>300)32
15		10	98	280–284 (208–212)19

^aIsolated yield.