Biomimetic semi-synthesis of fradcarbazole A and its analogues

The first synthesis of fradcarbazole A (1) has been accomplished by using a biomimetic intramolecular cyclization/dehydration to construct the staurosporine-thiazole-indole skeleton. The phenyl and oxazole analogues of fradcarbazole A (2-4) were also synthesized using the same strategy. Compounds 1-4 displayed cytotoxicity against A549 cell line with IC50 values of 0.4-3.6 μM, induction of G0/G1 arrest of A549 cell cycle at 10 μM, and inhibition of PKC-β kinase with IC50 values of 0.5-0.9 μM.