Enantioselective Preparation and Hydroboration of Cyclic Enamides: Synthesis of (2S)-Pseudoconhydrine

Article abstract of DOI:10.1016/0040-4039(95)00439-J

Successive treatment of 2-alkyl-1-hydroxy-6-carbonylsultampiperidines 1 with NaH and an acylating agent/pyridine in boiling toluene affords optically pure 1-acyl-2-alkyl-1,2,3,4-tetrahydropyridines 2.Hydroboration/oxidation of N-benzoylenamides 2f and 2g furnishes trans-2-alkyl-1-benzyl-5-hydroxypiperidines 5f and 5g, respecively.Hydrogenolysis of 5f provides pure (2S)-pseudoconhydrine (7), in 3 steps from 1, R²=n-C3H7 (31percent overall yield).