The Study Of The Synthesis Of Polysubstituted Pyrroles Via1,3-Dipolar Cycloaddition

Pyrrole and its derivatives are found in a variety of natural products, drugmolecules, and are also of growing relevance in material science. The study of synthesizing different pyrroles especially functionalized ones is of great interests in organic synthesis since wide applications of such compounds.Based on1,3-dipolar cycloaddition, this thesis mainly focused on the synthesis of multisubstituted pyrroles via1,3-dipolar cycloaddition of different azomethine ylides and aminophosphonates with alkynes. The thesis involves following two aspects:1. AgOAc catalyzed1,3-dipolar cycloaddition of glycine schiff bases and ynones.1,3-dipolar cycloaddition of glycine schiff bases and ynones catalyzed by AgOAc was established which could afford a series of2,3,5-trisubstituted pyrroles with the highest yield of89%. For some specific substrates, the reaction could proceed smoothly with the yield of51-69%when half of catalyst load was used. Furthermore, a series of experiments indicated that the mechanism of the reaction involved1,3-dipolar cycloaddition-aromatization cascade procedure. It was worth mentioning that no extra oxidant was needed in this highly atom-economical procedure.2.t-BuOK promoted1,3-dipolar cycloaddition of a-aminophosphonates with alkynes.By screening various bases, solvents, temperatures and other parameters, the novel1,3-dipolar cycloaddition of aminophosphonates with alkynes was presented. Under the optimized conditions, the target molecules could be obtained with the highest of73%yield. This mild and rapid reaction has provided a convenient and efficient method for the preparation of phosphoropyrroles.