Synthesis of N-protected staurosporinones.

Yasuhiro Wada, Hideo Nagasaki, Masao Tokuda, Kazuhiko Orito

Laboratory of Organic Synthesis, Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan.

The Journal of organic chemistry 2007 Mar 16

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We report a method for the synthesis of N-protected staurosporinones, which are useful for the synthesis of indolo[2,3-a]pyrrolo[3,4-c]carbazole alkaloids and related compounds. An interaction of gramine methiodide (2) with 3-(N-benzyl)indolylacetonitrile (3) in the presence of t-BuLi, followed by a CF3COOH-catalyzed intramolecular indole-indole coupling and dehydrogenation with DDQ, produced 5-cyanoindolo[2,3-a]carbazole 6 almost quantitatively. Reduction of its cyano group followed by N-benzylation produced N-benzylaminomethylindolo[2,3-a]carbazole 8b, which was subjected to Pd(OAc)2-catalyzed direct aromatic carbonylation to give N-protected staurosporinone 9b. Treatment with AlCl3 in anisole removed N-benzyl groups to afford staurosporinone quantitatively.

Citation

Yasuhiro Wada, Hideo Nagasaki, Masao Tokuda, Kazuhiko Orito. Synthesis of N-protected staurosporinones. The Journal of organic chemistry. 2007 Mar 16;72(6):2008-14