In contrast, our protocol involves combining all reactants -the carbonyl compound, the phosphonium salt and solid, easy-to-handle base KO t Bu -in a Teflon™ milling vessel containing one milling ball, without the need for air or moisture exclusion (Figure , bottom, left). The vessel is closed, mounted in a mixer mill, and ground for only 30 seconds at a frequency of 36 Hz. Typically, no pre-formation of the phosphonium ylide or sequential aldehyde addition is necessary to ensure a high-yielding olefination reaction. However, for highly base-sensitive substrates, ylide pre-formation with lower base-tophosphonium amounts can be conducted. In this modified approach, KO t Bu (1.2 equiv.) and PPh₃MeBr (1.4 equiv.) are ground for 1 minute at 36 Hz to form a yellow paste. The vessel is then opened, the carbonyl compound is added, and milling is continued until the reaction is complete.