Diastereo-Divergent Synthesis of Saturated Azaheterocycles Enabled by tBuOK-Mediated Hydroamination of Alkenyl Hydrazones

Diastereo-divergent synthesis of saturated azaheterocycles has been achieved by tBuOK-mediated hydroamination of alkenyl hydrazones. DFT calculations suggested that the cation-π interactions between a potassium cation and aryl substituents on hydrazones give rise to 2,5-cis selectivity in pyrrolidines, which were synthesized by the reaction of γ,δ-unsaturated N-benzyl hydrazones. By contrast, 2,5-trans selectivity was observed when an isopropyl group was used as the substituent on hydrazones. An unusual 2,6-trans selectivity in piperidine formation was also realized using the present strategy.