Table 2.

The effect of reaction condition on the synthesis of 5a

Entry	Solventa	Catalystb	Yieldc (%)
1	AcOH	–	47
2	MeOH	–	40
3	EtOH	–	44
4	DMF	AcOH	52
5	EtOH	AcOH	61
6	EtOH	Et3N	71
7	EtOH	Piperidine	71
8	Dioxane	NH4Cl	73
9	DMF	NH4Cl	75
10	MeOH	NH4Cl	87
11	EtOH	NH4Cl	92

The reaction was carried out with ethyl 2′-amino-3′-cyano-1-((diphenylamino)methyl)-6′-methyl-2-oxospiro[indoline-3,4′-pyran]-5′-carboxylate (3a) (10 mmol) and 2-hydroxybenzaldehydes (4a) (10 mmol)

^a10 mL solvent/reflux, 2 h

^b10 mol%

^cIsolated yields