Sequential Metal Catalysis towards 7-Oxostaurosporine and Its Non-Natural Septanose Analogue.

We report sequential metal catalysis towards indolocarbazole glycosides. The signature event is highlighted by i) Pd(0)-catalyzed addition of indolocarbazole to alkoxyallene combined with ring closing metathesis; ii) Ru-catalyzed chemoselective olefin migration; iii) Pd(II)-catalyzed oxidative cyclization to build the bicyclic core structure of the target compounds. This approach gave access to both natural pyranose- and non-natural septanose glycosides. A short formal synthesis of 7-oxostaurosporine was achieved via this strategy.