Synthesis of Polysubstituted Fused Pyrrolidines via [2+2]/[2+3] Cycloaddition of Azomethine Ylides

A general approach via [2 + 2]/[2 + 3] cycloaddition is elaborated for the preparation of densely substituted 3-azabicyclo[3.2.0]heptanes in good yields with excellent diastereoselectivities.