Table 1. Optimization of the Reaction Conditions.

entry	catalyst	time [h]	3aa [%]a	conv. [%]b
1		15	17	17
2	SO4/ZrO2	15	27	30
3	Amberlyst 15DRY	15	41	46
4	Nafion-H	15	45	52
5	H-ZSM-5	15	27	28
6	H–Y Zeolite	15	66	75
7	H-beta Zeolite	15	58	62
8	H-mordenite	15	73	78
9	H-mont	15	77	85
10	Fe-mont	15	74	85
11	Cu-mont	15	60	68
12	Zn-mont	15	66	77
13	Zr-mont	15	73	80
14	Sn-mont	15	66	75
15	H-mont	24	81	88
16c	H-mont	24	88 (86)d	96
17	PTSA·H2Oe	15	47	84

^aYield of 3aa was determined via gas chromatography (GC) analysis using n-tetradecane as an internal standard.

^bConversion of 1a was determined via GC analysis.

^c2a (2.2 mmol) was used.

^dIsolated yield.

^e5 mol % was used.