Cinchonidine-Catalyzed Synthesis of Oxazabicyclo[4.2.1]nonanones from N-Aryl-α,β-unsaturated Nitrones and 1-Ethynylnaphthalen-2-ols

A variety of oxazabicyclo[4.2.1]nonanone derivatives were prepared in good yields through a cinchonidine-catalyzed cascade reaction of N-aryl-alpha,beta-unsaturated nitrones and 1-ethynylnaphthalen-2-ols. Mechanistic studies show that the reaction undergoes a [4 + 3] cycloaddition of nitrones to vinylidene o-quinone methide generated in situ from 1-ethynylnaphthalen-2-ols in the presence of cinchonidine, 1,3-rearrangement of N-O vinyl moieties, ring-opening, and finally double intramolecular cyclizations to afford oxazabicyclo[4.2.1]-nonanones over five steps in a one-pot reaction.

Automated summary

A variety of oxazabicyclo[4.2.1]nonanone derivatives were synthesized in good yields through a cascade reaction, involving several steps, and a single-pot reaction. Mechanistic studies revealed the reaction pathway and the role of the catalyst in achieving the desired products.