Screening conditions for γ-hydroperoxy-γ-peroxylactone 2a synthesis^a.

Entry	Eq. H2O2	Acid, eq.	Yield 2a, %
1	10	BF3·Et2O, 10	54
2	10	SnCl4, 5	46
3	10	HClO4, 10	13
4	10	HBF4, 10	17
5	10	TsOH·H2O, 10	24
6	10	PMA, 1	15
7	10	BF3·Et2O, 5	38
8	10	BF3·Et2O, 2	19
9b	10	BF3·Et2O, 10	35
10	5	BF3·Et2O, 10	53
11	3	BF3·Et2O, 10	27

^aGeneral procedure: an ethereal solution of H₂O₂ (4.30 M, 0.698–2.326 mL, 3.0–10.0 mmol, 3.0–10.0 eq.) was added with stirring to a solution of 1a (234.3 mg, 1.00 mmol, 1.0 eq.) in Et₂O (3.5 mL). The mixture was cooled to 0 °C and acid was added dropwise with stirring. The reaction mixture was then stirred at 20–25 °C for 24 h.

^bCH₃CN as solvent.