Table 1. Optimization of the Reaction Times.

Entry	Reaction time	4 Yield (%)	Entry	Reaction time	4 yield (%)
1	0 min	2.00	11	2 h	2.95
2	10 min	2.46	12	3 h	3.00
3	20 min	2.77	13	4 h	3.01
4	30 min	2.87	14	5 h	2.74
5	40 min	3.35	15	6 h	2.67
6	50 min	3.42	16	7 h	2.63
7	60 min	3.86	17	8 h	2.54
8	70 min	3.64	18	9 h	2.46
9	80 min	3.53	19	10 h	2.38
10	90 min	3.20	20	11 h	2.10

*Reaction conditions: (−)-Sclareol 1 (10 mmol), Na₂WO₄·2H₂O (0.1 equiv), NaH₂PO₄ (0.1 equiv), TBAB (0.1 equiv), 1, 4-dioxane (7 mL), H₂O₂ (5 mL), 70 °C, 2 h; then rising to 90 °C; TBAB (Tetrabutyl ammonium bromide); GC yield.

Reaction time starts counting when the reaction system temperature rises to 90 °C.