Macroheterocyclization palladium mediated

The synthesis of diazepam and related 1,4-benzodiazepines has been accomplished by means of a palladium-catalysed carbonylation reaction. Similarly, this reaction has been employed as the key step for the construction of benz-lactams, in syntheses of anthramycin and of the lycorine ring system. Palladium-mediated macroheterocyclization has been used in an impressive synthesis of indandenin-12-one in a remarkable 23.3% overall yield from butadiene monoepoxide. The key step provided the necessary 21-membered ring in nearly quantitative yield in a highly chemo-, regio-, and stereo-selective fashion (Scheme 41). ... 

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