- Synthesis of β- and γ-carbolines by the palladium-catalyzed iminoannulation of alkynes
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A variety of substituted β- and γ-carbolines have been prepared in moderate to excellent yields by the palladium-catalyzed annulation of internal and terminal acetylenes by the tert-butylimines of N-substituted 3-iodoindole-2-carboxaldehydes and 2-haloindole-3-carboxaldehydes, respectively. This annulation chemistry is effective for a wide range of alkynes, including aryl-, alkyl-, hydroxymethyl-, ethoxycarbonyl-, and trimethylsilyl-substituted alkynes. When an unsymmetrical internal alkyne is employed, this method generally gives two regioisomers. When a terminal alkyne is employed, only one regioisomer has been isolated. This palladium-catalyzed annulation chemistry has also been successfully applied to the synthesis of two biologically interesting β-carboline alkaloids, ZK93423 and abecarnil (ZK112119).
- Zhang, Haiming,Larock, Richard C.
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- A mild and efficient dehydrogenation method for 3-carboxy-1,2,3,4-tetrahydro-β-carbolines
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A new mild and efficient method for the dehydrogenation of 3-carboxytetrahydro-β-carbolines using trichloroisocyanuric acid (TCCA) / triethylamine (TEA) has been developed.
- Haffer, Gregor,Nickisch, Klaus,Tilstam, Ulf
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