DABCO Catalyzed Synthesis of Xanthene Derivatives in Aqueous Media

Table 2

Synthesis of heteroaryl substituted xanthenes and its alkylidene derivatives^a,b.

Entry	X	R1	R2	Time (min)	Product	Yield (%)^c	M.P (°C)
1	O	H	H	30	1a	94	168-169
2	O	H	CH3	30	1b	92	158–160
3	S	H	H	30	1c	95	142–144
4	S	CH3	H	30	1d	96	156-157
5	S	H	CH3	30	1e	94	145–147
6	NH	H	H	30	1f	87	88–90
7	O	H	H	60	2a	78	212-213
8	O	H	CH3	60	2b	76	183–185
9	S	H	H	60	2c	81	197-198
10	S	CH3	H	60	2d	77	170–172
11	S	H	CH3	60	2e	83	177–179
12	NH	H	H	60	2f	87	112–114

^aReaction conditions: heteroarylaldehyde (1 mmol), dimedone (2 mmol), and DABCO (10 mmol%) in water (20 mL) under reflux temperature. ^bReaction conditions: 1a–f (1 mmol), malononitrile (2 mmol), and DABCO (10 mmol%) in water (20 mL) under reflux temperature. ^cIsolated yields.