Catalyst-Free Synthesis of Highly Biologically Active 5-Arylidene Rhodanine and 2,4-Thiazolidinedione Derivatives Using Aldonitrones in Polyethylene Glycol

Table 1

Synthesis of 5-arylidine rhodanine and 2,4-thiazolidinedione derivatives using aldonitrones in polyethylene glycol (PEG).

Entry	X	Y	Product^a	Time (min)	Yield (%)^b	Melting point (°C) reference
1	H	S	3a	20	85	202-203 [11]
2	4-Cl	S	3b	20	93	230–232 [11]
3	4-Br	S	3c	20	89	229-230 [3]
4	4-NO2	S	3d	25	94	254-255 [11]
5	4-CH3	S	3e	30	78	224-225 [11]
6	4-CH3O	S	3f	30	83	250-251 [11]
7	4-OH	S	3g	30	79	184-185 [35]
8	H	O	3h	25	92	240-241 [36]
9	3-Cl	O	3i	25	88	270-271 [36]
10	4-Cl	O	3j	25	85	224-225 [37]
11	4-NO2	O	3k	25	75	260–262 [37]
12	4-CH3	O	3l	25	86	224-225 [37]
13	4-CH3O	O	3m	35	88	234-235 [36]
14	4-OH	O	3n	35	90	280-281 [36]

^aReaction conditions: 1a–h (10 mmol), 2a-b (10 mmol), and polyethylene glycol (PEG) 5 mL were heated at 80^˚C on magnetic stirrer. The products were characterized by spectral techniques like IR, ¹H NMR. ^bIsolated yields after recrystallization.