Entrapment and Kinetic Resolution of Stabilized Axial and Equatorial Conformers of Spiro-β-lactams

The facile synthesis of the stabilized axial and equatorial conformers
of spiro-β-lactams was achieved via entrapment of cyclohexanone
imines (Schiff bases) with acetoxyacetyl chloride in a [2 + 2]-cycloaddition
reaction followed by their kinetic resolution. The immobilization
of the racemic substrates on an inert solid support significantly
reduced the reaction time and improved the enantioselectivity of conformers
during kinetic resolution. The mechanism of the formation of the spiro-β-lactams
was explored using B3LYP/6-31+G* level quantum chemical calculations.