Diastereoselective Synthesis of High Functionalized 4‐Imidazolidinone‐Tetrahydro‐β‐Carboline Hybrids via Divergent Post‐Ugi Transformation

An easily scalable and highly diastereoselective synthesis of challenging 1,2,5,6,11,11b-hexahydro-3H-imidazo[1′,2′:1,2]pyrido[3,4-b]indol-3-ones is accomplished through divergent transformation of Ugi 4-CR products. The trimethylsilyl trifluoromethanesulfonate (TMSOTf) mediated intramolecular condensation of a series of Ugi 4-CR adducts generates a N-acylimidinium intermediate which undergoes ring closure to selectively afford the target title compounds in good to high yields.