General procedure for Wittig olefination with ylide pre-formation A 7 mL Teflon™ milling vessel equipped with one 12 mm stainless steel ball, was charged with the respective phosphonium halide (0.7 mmol, 1.4 equiv.), and potassium tert-butoxide (0.6 mmol, 1.2 equiv.). The closed Teflon™ vessel was mounted into the holding station of an IST636 mixer mill and milling was conducted at a frequency of 36 Hz for 1 minute. Subsequently, the milling vessel was opened, and the aldehyde/ketone substrate (0.5 mmol, 1 equiv.) was added to vessel. The vessel was closed and mounted again into the mixer mill's holding station and milling process was continued at 36 Hz for additional 30 seconds.