A novel heterogeneous acid–base nano-catalyst designed based on graphene oxide for synthesis of spiro-indoline-pyranochromene derivatives

Table 1 Optimization of the reaction conditions for synthesis of spiro-indoline-pyranochromene derivatives^a

Entry	Catalyst	Solvent	Temp. (°C)	Time (min)	Weight catalyst(g)	Yield (%)
1	–	EtOH:H₂O (1:1)	r.t	60	–	40
2	GO	EtOH:H₂O (1:1)	r.t	40	0.04	56
3	3-aminopyridine	EtOH:H₂O (1:1)	r.t	40	0.04	87
4	Nano-GO/3-aminopyridine	EtOH:H₂O (1:1)	r.t	30	0.04	85
5	Nano-GO/3-aminopyridine	H₂O	r.t	40	0.04	70
6	Nano-GO/3-aminopyridine	EtOH	r.t	15	0.04	90
7	Nano-GO/3-aminopyridine	Solvent-free	r.t	20	0.04	95
8	Nano-GO/3-aminopyridine	Solvent-free	70	20	0.04	95
9	Nano-GO/3-aminopyridine	Solvent-free	r.t	20	0.05	95
10	Nano-GO/3-aminopyridine	Solvent-free	r.t	37	0.03	80
11	Nano-GO/3-aminopyridine	Solvent-free	r.t	45	0.02	70

ISSN: 2661-801X