Table 3. Substrate Scope for Several Chromeno[4,3-d]pyrido[1,2-a]pyrimidin-6-one Derivatives 8a-q^a.

entry	substituent (R)	product	time (h)	yieldb (%)	melting point (°C)
					determined	reported47,48
1	C6H5	8a	2.5	93	206–208	211–212
2	2-ClC6H4	8b	6	78	238–240	242–244
3	3-ClC6H4	8c	4.5	84	179–181	177–178
4	4-ClC6H4	8d	3.5	92	236–238	255–257
5	3-OHC6H4	8e	5.5	71	147–149	new
6	4-OHC6H4	8f	3.5	94	156–158	157–158
7	4-CH3C6H4	8g	4	92	225–227	229–230
8	3-FC6H4	8h	5	75	201–203	new
9	4-FC6H4	8i	2.5	94	218–220	224–225
10	4-OCH3C6H4	8j	4	89	223–225	206–207
11	3-BrC6H4	8k	7	80	205–207	new
12	4-BrC6H4	8l	2	91	235–237	240–242
13	2-furyl	8m	6	87	171–173	175–176
14	4-CNC6H4	8n	4	93	218–220	228–229
15	3,4-(OCH3)2 C6H3	8o	4	85	208–210	215–216
16	3,4-(OH)2C6H3	8p	8	92	177–179	180–181
17	4-N(CH3)2C6H4	8q	10	84	181–183	182–183
18	acetaldehyde		18	n.r.
19	propionaldehyde		18	n.r.
20	butyraldehyde		18	n.r.

^aOne-pot reaction performed using 5 (1 equiv), 6 (1 equiv), and 7 (1 equiv) at room temperature in aq. EtOH (1:1). 5 mol % catalyst.

^bYield of the isolated product. n.r.—no reaction