Synthesis of N-protected staurosporinones.
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.
Wada
Yasuhiro
Y
Laboratory of Organic Synthesis, Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
Nagasaki
Hideo
H
Tokuda
Masao
M
Orito
Kazuhiko
K
D002227:Carbazoles / Q000138:chemical synthesis*; D002384:Catalysis; D026121:Indole Alkaloids / Q000138:chemical synthesis*; D007211:Indoles; D007659:Ketones / Q000138:chemical synthesis; D019311:Staurosporine / Q000138:chemical synthesis*
D002227:Carbazoles; D026121:Indole Alkaloids; D007211:Indoles; D007659:Ketones; C049985:staurosporine aglycone; D019311:Staurosporine