Conditions optimization for the bromocycloetherification.

Entrya	Frequency	Time	Yield (%)b
1	15 Hz	10 min	58
2c	—	10 min	2
3	30 Hz	10 min	69
4	30 Hz	30 min	85
5	30 Hz	60 min	99 (98)d

^aReactions were conducted using a Retsch mixer mill (MM 400) in a 10 mL zirconium oxide chambers with olefinic alcohol 5a (0.2 mmol) and NBS (0.22 mmol) at ambient temperature in the absence of light.

^bYields were acquired by NMR spectroscopy with dibromomethane as the internal standard.

^cReaction was conducted in CH₂Cl₂ (0.2 M).

^dIsolated yield.