Synthesis and Biological Evaluation of ABCD Ring Fragments of the Kibdelones

Arylation goes platinum: The synthesis of the ABCD ring fragments of the kibdelones has been achieved through a novel PtIV-catalyzed arylation of a quinone monoketal followed by photocyclization (see scheme). Biological evaluation in the NCI 60-cell screen revealed that the kibdelone ABCD ring analogues were about 2000 times less active than kibdelones B and C, suggesting that the tetrahydroxanthone structure of the kibdelones is crucial for cytotoxicity.