Application of the ring-closing metathesis to the formation of 2-aryl-1 H -pyrrole-3-carboxylates as building blocks for biologically active compounds

Ring-closing metathesis (RCM) is a powerful tool for the preparation of cyclic organic compounds. Yet, one of the major limitations of this method is the difficulty to prepare large quantities of target molecules. Herein we describe a comprehensive study regarding the gram-scale synthesis of 2-aryl-1 H -pyrrole-3-carboxylates based on the ring-closing metathesis of the corresponding β-amino esters as a key step. This study includes evaluation of solvent and catalyst as well as reaction kinetics on the RCM. After an aromatization step, this methodology allowed for an efficient generation of variously substituted and unprecedented 2-aryl-1 H -pyrrole-3-carboxylates in good yields and cost-effectiveness. The resulting molecules might serve as key building blocks for the generation of CNS-oriented compound libraries.