Remote stereocenter discrimination in the enzymatic resolution of piperidine-2-ethanol. Short enantioselective synthesis of sedamine and allosedamine.

Kinetic resolution of N-Boc-piperidine-2-ethanol (2), a case of remote stereocenter discrimination, was accomplished by sequential transesterification mediated by two enzymes, Lipase PS and porcine pancreatic lipase, showing opposite enantioselectivity. The gram-scale availability of the two enantiomeric N-Boc alcohols 2a (R) and 2c (S) enlarges their synthetic exploitation for the enantioselective preparation of piperidine alkaloids. As an example, the convenient three-step synthesis of both the enantiomers of sedamine and allosedamine is described.

Concise total synthesis of (+/-)-aloperine and 6-epi-aloperine.

[reaction: see text] Total synthesis of aloperine and 6-epi-aloperine is reported. The crucial steps of the synthetic strategy are an aza-annulation reaction and an intermolecular Diels-Alder reaction. The synthetic plan proceeds from commercially available piperidine-2-ethanol.