Abstract
Cyclocondensation between acyclic 5-aminopent-2-enoate esters
and aliphatic aldehydes containing an unsubstituted α-methylene
unit affords 1,2,3,4-tetrahydropyridine derivatives in good yields.
The reaction has been applied to a range of aldehydes, showing good
functional group tolerance. Chemoselective hydride reduction of
the enamine double bond provides 3,4-disubstituted tertiary piperidine
derivatives with acceptable to good diastereoselectivities, whereas
catalytic hydrogenation of N-benzyl derivatives leads directly to
the corresponding secondary piperidines.
Key words
condensation - cyclizations - reductions - piperidines - stereoselective synthesis
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