The origins of contrasteric diastereoselectivity in the epoxidation of encumbered
tetrahydropyridines have been elucidated via density functional theory (DFT) calculations.
A strong energetic preference for OH···N hydrogen bonding was found for epoxidation
transition states of the unsubstituted tetrahydropyridine. For hexasubstituted tetrahydropyridines,
the diastereofacial selectivity is dictated by both the strong OH···N hydrogen bonding
and the conformational preference of the tetrahydropyridine substrate.
Key words
DFT calculation - heterocycles - piperidines - epoxidation - stereoselective synthesis