Greener and facile aqueous synthesis of pyrazoles using Amberlyst-70 as a recyclable catalyst

Figures & data

Figure 1.  Amberlyst-70 catalysed synthesis of pyrazoles.

Figure 2.  The effect of different catalyst on the condensation of acetylacetone and phenylhydrazine.

Figure 3.  Recycle study of Amberlyst-70 for the reaction of acetylacetone with phenyl hydrazine.

Table 1. Amberlyst-70 catalyzed synthesis of pyrazoles at room temperature in aqueous medium.

Entry	R ^1	X	R ^2	Product	Yield^a (%)
1	CH3	H	Ph	3a	94
2	CH3	H	H	3b	89
3	CH3	H	4Cl-Ph	3c	97
4	CH3	H	NH2CO	3d	96
5	CH3	H	NH2CS	3e	97
6	OEt	CH3	Ph	4a	85
7	OEt	CH3	H	4b	91
8	OEt	CH3	4Cl-Ph	4c	80
9	OEt	CH3	NH2CO	4d	94
10	OEt	CH3	NH2CS	4e	89
11	OEt	Cl	Ph	5a	97
12	OEt	Cl	H	5b	93
13	OEt	Cl	4Cl-Ph	5c	98
14	OEt	Cl	NH2CO	5d	85
15	OEt	Cl	NH2CS	5e	91
16	OEt	H	Ph	6a	80
17	OEt	H	H	6b	88
18	OEt	H	4Cl-Ph	6c	95
19	OEt	H	NH2CO	6d	86
20	OEt	H	NH2CS	6e	94
^aIsolated yields.