Copper-catalyzed [3 + 2] cycloaddition reactions: synthesis of substituted pyrazolo[1,5-c]quinazolines with N-iminoquinazolinium ylides and olefins as starting materials†
Abstract
Here we describe a copper-catalyzed [3 + 2] cycloaddition reaction between N-iminoquinazolinium ylide and various polar olefins in mild conditions. In this process, pyrazolo[1,5-c]quinazoline derivatives were efficiently synthesized via cycloaddition followed by oxo-dehydrogenation in moderate to good yield.