Catalytic asymmetric homo-1,3-dipolar cycloadditions of azomethine ylides: diastereo- and enantioselective synthesis of imidazolidines

摘要

The first catalytic asymmetric homo-1,3-dipolar cycloadditions of azomethine ylides have been established via SPINOL-derived chiral phosphoric acid-catalyzed pseudo four-component reactions of aldehydes and 2-aminomalonates, resulting in the stereoselective construction of chiral imidazolidine scaffolds with two stereogenic centers in generally high yields and with good stereoselectivities (up to 81% yield, all >20:1 dr, up to 93% ee). This protocol provides easy access to synthetically and pharmaceutically important chiral imidazolidines via the formation of one ring system, two stereogenic centers, and four new bonds in a single step.