Rhodium(III)‐catalyzed double C−H annulation of 3‐(acetylamino)coumarins with internal arylacetylenes is reported. The reaction proceeds smoothly accompanied by two C−C and two C−N bond formation to produce 8‐aryl‐6H‐chromeno[4’,3’:4,5]pyrrolo[2,1‐a]isoquinolin‐6‐ones selectively. It also provides a straightforward route to natural product inspired pentacyclic pyrrolocoumarin derivatives from readily available building blocks.
The direct annulative coupling of 3-(acetylamino)thiophenes with internal alkynes proceeds smoothly under rhodium catalysis through acetylamino-directed C-H bond cleavage at the C2-position to lead to the effective construction of 4-acetylthieno[3,2-b]pyrrole derivatives. The acetyl directing group on the annulation product is readily removable to produce 4-unprotected thieno[3,2-b]pyrrole derivative.
The dehydrogenative coupling of 2-(acetylamino)-1,1'-biphenyls with internal alkynes proceeds regioselectively under rhodium catalysis to afford the corresponding 7-phenylindole derivatives. Combining with Suzuki-Miyaura coupling, the processes provide easy access to the 7-phenylindole structures from readily available starting materials.
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