Chiral phosphoric acid catalyzed addition of dihydropyrans to N-acyl imines: stereocontrolled access to enantioenriched spirocyclic oxazoletetrahydropyrans with three contiguous stereocenters

Chiral phosphoric acid catalyzed addition of dihydropyrans to N-acyl imines: stereocontrolled access to enantioenriched spirocyclic oxazoletetrahydropyrans with three contiguous stereocenters