Stereocontrolled Access to Orthogonally Protected <i>anti</i>,<i>anti</i>-4-Aminopiperidine-3,5-diols through Chemoselective Reduction of Enantiopure β-Lactam Cyanohydrins
either molecular sieves or catalytic amount of sodium carbonate to give O-silylated β-lactam cyanohydrins with good yield and diastereoselectivity. In contrast, Lewis acids did not effectively promote the cyanosilylation under different experimental conditions, and instead hydrocyanation took place affording the corresponding free cyanohydrins in variable yield and selectivity. Starting from β-lactam