Further optimization showed that the milling time could be reduced to as short as 30 seconds, with the aldehyde (I) still showing full conversion (entry A6). Consequently, 30 seconds was selected as the preferred reaction time, despite giving a lower yield compared to the other data points (entry A2 -A5). At a shorter milling time of 10 seconds, unreacted aldehyde was still present in the reaction mixture (entry A7). Without mechanical impact (0 seconds) starting material could be quantitatively recovered (entry A8). This blank experiment confirms that the reaction is not taking place during workup procedures, but that the conversion of I to 1 is indeed mechanochemically induced.