Ball Milling
H O R (S)proline 10 mol% Ball milling (A) or stirring (B) H R Entry R= Method t/h Yield% anti/syn ee% 1 4NO 2 A 99 89:11 94 2 4NO 2 B 24 95 89:11 94 3 3NO 2 A 7 94 88:12 >99 4 3NO 2 B 16 89 82:18 98 5 2NO 2 A 7 97 93:7 97 6 2NO 2 B 36 89 91:9 97