Diazonamide second total synthesis

Nicolaou KC, Hao J, Reddy MV, Rao PB, Rassias G, Snyder SA, Huang X, Chen D Y-K, Brenzovich WE, Giuseppone N, Giannakakou P, O Brate A (2004) Chemistry and Biology of Diazonamide A Second Total Synthesis and Biological Investigations. J Am Chem Soc 126 12897... 

An improved procedure for the rapid synthesis of aryl dihydrobenzofurans with a boron tribromide-mediated cyclization was discussed and is shown below <03HCA343>. In the second total synthesis of diazonamide A, the late key step accounting for the dihydrobenzofuran formation was a DIBAL-H mediated lactam reduction and cyclization <03AG(E)1753>. 

Scheme 17. Final steps and completion of the second total synthesis of diazonamide A (1).

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