Synthesis of two series of pyrazolic analogues of the marine alkaloids granulatimide and isogranulatimide as potent Checkpoint 1 kinase inhibitors

Two series of regioisomeric pyrazolic analogues of the marine alkaloids granulatimide and isogranulatimide were prepared. The synthesis of the first series was based on the condensation reaction of diversely 5-substituted 3-bromoindoles with pyrazole followed by addition of the intermediates on dibromomaleimide, the so-obtained acyclic adducts being finally photochemically cyclised to the desired analogues. Compounds of the second series were obtained by reacting different 5-substituted-indole-3-glyoxylates with N-Boc-pyrazole-3-acetamide and subsequent photochemical cyclisation of the adducts.