Fig. 6: Synthetic explorations of the 1,4-cycloadduct, 3eD.

(a) Hydrogenation with Pd/C and ammonium formate. (b) Formal 1,3-dipolar cycloaddition with nitrile oxide. (c) Wagner–Meerwein-type rearrangement with NBS in acetone-water.

(a) Hydrogenation with Pd/C and ammonium formate. (b) Formal 1,3-dipolar cycloaddition with nitrile oxide. (c) Wagner–Meerwein-type rearrangement with NBS in acetone-water.