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Direct Construction of Bicyclic Heterocycles by Palladium-Catalyzed Domino Cyclization of Propargyl Bromides

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posted on 20.03.2008, 00:00 by Hiroaki Ohno, Akinori Okano, Shohei Kosaka, Koji Tsukamoto, Miyo Ohata, Kotaro Ishihara, Hatsuo Maeda, Tetsuaki Tanaka, Nobutaka Fujii
The palladium-catalyzed domino cyclization of propargyl bromides having two nucleophilic functional groups is described. Treatment of 1,7-diamino-5-bromohept-3-yne derivatives with catalytic Pd(PPh3)4 in the presence of NaH in MeOH gives the 2,7-diazabicyclo[4.3.0]non-5-enes in good yields. Interestingly, the regioselectivity of the reaction is completely controlled by the relative reactivity of the amine functional groups, irrespective of the position of the nucleophiles. The malonate derivative also undergoes domino cyclization to produce a hexahydroindole derivative.