Palladium-Catalyzed Cross-Coupling of Aryl Iodides with Heterobicyclic Olefins: Access to Hydroarylated and Heteroannulated Motifs

摘要

Transition metal catalyzed synthetic transformations of bicyclic olefins have acquired considerable attention towards the construction of biologically relevant carbocycles and heterocycles. In this regard, urea derived bicyclic olefins grabbed our attention due to its tremendous biological significance and synthetic potential. Herein, we report a palladium catalyzed reductive Heck reaction of urea-derived bicyclic olefins toward the synthesis of hydroarylated and heteroannulated motifs using aryl iodides. The reaction of aryl iodides in the presence of a hydrogen donor such as formic acid furnished the hydroarylated products in moderate to excellent yields. Heteroannulated products such as dihydrobenzofuran derivatives were obtained in moderate to good yields with 2-iodophenols in the absence of a hydrogen donor. We were also successful in extending this strategy to 2-iodobenzylbromide and 2-iodobenzonitrile towards the synthesis of ring fused indane and indanone derivatives. To our dismay, the reactions with 2- iodoaniline to provide the expected indoline derivatives remained futile. The presence of biologically significant urea moieties coupled with naturally as well as pharmaceutically prevalent carbo/heterocyclic derivatives in the products authenticate the relevance of the current synthetic strategy.