Catalyst-Enabled Scaffold Diversity: Highly Chemo- and Stereoselective Synthesis of Tricyclic Ketals and Triarylmethanes

The first catalytic cascade reaction of activated isocyanides with para-quinone methide-aryl esters is presented. Catalyst-enabled divergent pathways have also been achieved to deliver skeletally diverse products. While Ag catalysis leads to an unprecedented highly diastereoselective synthesis of tricyclic ketals, a simple procedure employing Cu catalysis produces oxazole-containing triarylmethanes in high efficiency through an unexpected C–C bond cleavage.