Rh(III)-Catalyzed C–H Activation of Benzoylacetonitriles and Tandem Cyclization with Diazo Compounds to Substituted Benzo[de]chromenes.

Rh (III)-catalyzed C–H activation of benzoylacetonitriles in coupling with diazo compounds was developed to synthesize diversified substituted benzo[de]chromenes via a formal (4 + 2) cycloaddition with a diazo compound and subsequent tandem (4 + 2) cycloaddition with another diazo compound. Intriguingly, synthesis of substituted benzo[de]chromenes and their decarboxylation products could be realized by controlling the reaction conditions. These reactions have a broad range of substrates, moderate to good yields, and high regioselectivity. [ABSTRACT FROM AUTHOR]