Green synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazoles] using Fe 3 O 4 @ l -arginine as a robust and reusable catalyst

Table 3 Synthesis of spiro[indoline-3,4′- pyrano[2,3-c]pyrazole] derivatives using Fe₃O₄@l-arginine under solvent-free conditions

Entry	Product	Yield (%)^a	M.p. °C	Lit. M.p. °C
1	5{1,1,1,1}	96	286–288	285–286 [18]
2	5{1,1,2,1}	91	297–298	297–298 [18]
3	5{1,1,3,1}	95	283–285	282–283 [18]
4	5{2,1,1,1}	90	225–227	227–229 [18]
5	5{1,2,3,1}	91	257–259	256–257 [18]
6	5{1,2,1,1}	90	282–284	280–281 [18]
7	5{1,2,1,2}	87	240–242	242–243 [18]
8	5{1,2,3,2}	89	256–258	257–259 [18]
9	5{1,2,2,2}	85	266–268	265–267 [18]
10	5{1,1,4,1}	94	278–280	279–281 [18]
11	5{1,2,4,1}	86	246–248	247–249 [18]
12	5{1,2,4,2}	87	262–264	260–263 [18]
13	5{2,1,4,1}	89	220–222	222–224 [18]
14	5{2,1,3,2}	92	212–214	–^b
15	5{2,1,2,2}	90	279–281	–^b
16	5{2,1,4,2}	97	198–200	–^b