Enantioselective Synthesis of Benzimidazolyl Quinoxalinones on Soluble Polymer Support Using Focused Microwave Irradiation

Abstract

Focused microwave irradiation has been applied to a multistep synthetic sequence of reactions designed to generate benzimidazolyl quinoxalinones using a soluble polymer support. They were obtained by the ipso-fluoro (S(N)Ar) displacement of the immobilized ortho-nitro fluoro benzimidazoles with chiral alpha amino esters under microwave irradiation. Intermediate chiral organic-polymer conjugates when subjected to neutral reduction underwent a spontaneous intramolecular ring closure. Cleavage of the polymer support, at room temperature, did not cause any significant racemization resulting in the generation of a chiral molecular library with two points of structural diversity.