Table 1.

Optimization of the Reaction Conditions^a

entry	substrate	conditionsa	ratio of 1:2:3b	yield of 3 (%)c
1	1·HBF4	m-CPBA, CH2Cl2, rt	1:5:0	—
2	1·HBF4	H2O2, AcOH, 80 °C	0:1:0	—
3	1·HBF4	DMDO, CH2Cl2, rt	11:0:1	—
4	1·HBF4	H2O2, 4 (20 mol %)	1:0:5	77%
5	1	HBF4·OEt2, H2O2, 4 (20 mol %)	1:0:4	77%
6	1	HBF4·OEt2, H2O2	1:0:0	—
7	1	HBF4·OEt2, m-CPBA	2:5:0	—
8	1	H2O2, 4 (20 mol %)	0:1:0	—
9	1	H2SO4, H2O2, 4 (20 mol %)	—	66%
10	1	HBF4·OEt2, DMDO	—	15%

^aOne equivalent of oxidant was used for entries 1, 3, 7, and 10. Two equivalents were used for entries 4–6, 8, and 9. Four equivalents were used for entry 2. For entries 4–10, a 5:1 mixture of CH₂Cl₂:HFIP was used as the solvent, and the reactions were run at room temperature.

^bRatios determined by integration of HPLC chromatograms.

^cIsolated yield.