An Atom-Economical Approach to Conformationally Constrained Tricyclic Nitrogen Heterocycles via Sequential and Tandem Ugi/Intramolecular Diels-Alder Reaction of Pyrrole
An efficient approach to rigid tricyclic nitrogen heterocycles via sequential and tandem Ugi/intramolecular Diels-Alder (IMDA) cycloaddition of pyrrole is described. The one-pot Ugi four-component condensation (4CC) reaction was used as the key transforma