Table 3.

Synthesis of PHA derivatives 5a-l from different aldehydes 2a-l catalyzed by the Cs/ECH-TMA organocatalyst (1) under optimized conditions.^a

Entry	Aldehyde 2	Product 7	Time (min)	Yield (%)	M.P/Obs. (oC)	M.P/Rep. (oC)
1	4-Chlorobenzaldehyde (2a)	5a	25	95	306–308	303 ‒ 305 [98]
2	2,4-Dichlorobenzaldehyde (2b)	5b	25	94	319–322	321 [99]
3	4-Nitrobenzaldehyde (2c)	5c	40	84	301–303	302 ‒ 305 [100]
4	4-Hydroxy-3-methoxybenzaldehyde (2d)	5d	35	88	293–296	295 ‒ 298 [101]
5	3-Nitrobenzaldehyde (2e)	5e	40	80	292–294	294 ‒ 296 [102]
6	4-Florobenzaldehyde (2f)	5f	25	96	246–248	246 ‒ 248 [103]
7	Benzaldehyde (2g)	5g	25	92	190–191	189 ‒ 191 [103]
8	2-Chlorobenzaldehyde (2h)	5h	25	92	222–224	221 ‒ 222 [104]
9	4-Methoxybenzaldehyde (2i)	5i	25	86	295–297	296 ‒ 298 [105]
10	4-Hydorxybenzaldehyde (2j)	5j	25	87	303–305	>300 [106]
11	4-Methylbenzaldehyde (2k)	5k	25	89	300–302	>300 [106]
12	2-Bromobenzaldehyde (2l)	5l	25	90	253–255	252 ‒ 254 [107]

^bAll products are known and their structures were established from their spectral data and melting points compared to authentic samples or literature values.

^cIsolated yields.

^aReaction conditions: Dimedone (3, 2.0 mmol), aryl aldehydes (2, 1.0 mmol), NH₄OAc (5, 1.2 mmol) and the Cs/ECH-TMA (1, 10 mg) in EtOH under reflux conditions.