Table 2.

Q-tube [4 + 2] cyclocondensation reactions of 4-thiazolidinone 4a-c and arylhydrazonal 5.

Entry	Reactants	Ar1	Ar2	X	Product	Yield (%)a
1	4a + 5a	C6H4	C6H5			98
2	4a + 5b	C6H4	4-Cl-C6H4			99
3	4a + 5c	C6H5	4-NO2-C6H4			94
4	4a+5d	C6H5	4-MeO-C6H4			95
5	4a + 5e	4-Cl-C6H4	4-Cl-C6H4			96
6	4a + 5 f	4-Cl-C6H4	2-Cl-5-NO2-Ph			98
7	4a + 5 g	4-Br-C6H4	2-Cl-5-NO2-Ph			97
8	4a + 5 h	4-Br-C6H4	2,4-diF-C6H3			94
9	4a + 5i	4-F-C6H4	4-Me-C6H4			92
10	4a + 5j	C10H7	4-Cl-C6H4			96
11	4a + 5k	C10H7	4-NO2-C6H4			95
12	4a + 5 l	C10H7	4-NO2-C6H4			93
13	4a + 5 m	C4H3S	C6H5			92
14	4a + 5n	C4H3S	4-Cl-C6H4			93
15	4a + 5o	C4H3O	2-Cl-5-NO2-Ph			90
16	4a + 5p	N-Me-Ind	4-NO2-C6H4			91
17	4b + 5a	C6H5	C6H5			91
18	4b + 5e	4-Cl-C6H4	4-Cl-C6H4			94
18	4b + 5c	C6H5	4-NO2-C6H4			92
19	4c + 5a	C6H5	C6H5			88
20	4c + 5b	C6H5	4-Cl-C6H4			89

^aReaction conditions: a mixture 4-thiazolidinone 4a-c (5 mmol), arylhydrazonal 5 (5 mmol), anhydrous sodium acetate (10 mmol) and glacial acetic acid (10 mL) was charged in the glass tube of the Q-tube reactor and heated in an oil bath at 170 °C for 25 min.