Table 3.

Preparation of 4H-pyrans derivatives by using Cu₂(NH₂-BDC)₂(DABCO) as the catalyst^a

.

Entry	Aldehyde	Product	Time (min)	Yield (%)b	M.P. (°C)	M.P. (°C) [Lit.]
1	4-Chloro benzaldehyde	8a	22	92	160–163	162 [55]
2	2-Chloro benzaldehyde	8b	25	90	188–192	190-191 [56]
3	4-Bromo benzaldehyde	8c	25	92	179–182	179-180 [57]
4	Benzaldehyde	8d	60	80	185–188	189 [58]
5	2-Nitro benzaldehyde	8e	42	90	178–180	177-178 [57]
6	3-Nitro benzaldehyde	8f	40	87	186–190	187-188 [57]
7	4-Nitro benzaldehyde	8g	40	89	175–178	174-176 [59]
8	4-Methyl benzaldehyde	8h	18	90	173–176	175-176 [59]
9	4-Chloro benzaldehyde	9a	30	65	149–154	153-155 [60]
10	3-Nitro benzaldehyde	9b	42	63	160–164	166 [61]

^aReaction conditions: aldehyde (2, 1.0 mmol), malononitrile (3, 1.0 mmol), acetyl acetone or ethyl acetoacetate (7a-b, 1.0 mmol), Cu₂(NH₂-BDC)₂(DABCO) (0.04 g), solvent-free and room Temperature.

^bIsolated yield.