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A metal-free expeditious strategy for the divergent synthesis of structurally diverse bicyclic imidazo[1,5-a]pyrazine and imidazo[1,5-a][1,4]diazepine scaffolds is disclosed by combining an Ugi four-component reaction of easily available building blocks and an exo/endo selectivity-switchable post-Ugi [a] 7678 [a] All the reactions were run with 5a (0.05 mmol), phosphines and 1.0 mL of solvent in a sealed vial. [b] Yields are determined by 1 H NMR spectroscopy using 2,4,6-trimethoxybenzaldehyde as internal standard. [c] Isolated yields.