Novel ZrOCl₂·8H₂O-Catalysed One-Pot Multicomponent Synthesis of 9,10-Dihydro-8H-benzo[a]xanthen-11(12H)-one Derivatives

Table 1

Screening of the catalyst and solvent for the reaction of 𝛽-naphthol, benzaldehyde, and 5,5-dimethylcyclohexane-1,3-dione catalyzed by ZrOCl₂·8H₂O^a.

Entry	Catalyst (mol%)	Solvent/condition	Time (h)	Yield^b (%)
1	20	Water/80°C	10	—
2	20	THF/Reflux	10	—
3	20	CH3CN/Reflux	10	<10
4	20	CH3NO2/Reflux	10	15
5	20	CHCl3/Reflux	10	15
6	20	DMF/80°C	10	55
7	20	CH2Cl2/Reflux	10	65
8	20	(bmim) BF4/Reflux	5	75
9	20	None/80°C	10	20
10	20	CH3CH2OH/rt	4	85
11 𝐜	20	𝐂𝐇𝟑𝐂𝐇𝟐𝐎𝐇 /Reflux	1	92, 93, 92, 92, 91
12	10	CH3CH2OH/Reflux	10	80
12	30	CH3CH2OH/Reflux	4	92
10	none	CH3CH2OH/Reflux	10	Nil

aReaction conditions: 𝛽-naphthol (1.0 mmol), benzaldehyde (1.0 mmol), and 5,5-dimethylcyclohexane-1,3-dione (1.1 mmol), zirconium oxychloride catalyst.
^bIsolated yield.
^cCatalyst was reused five times.