Total synthesis of amino-functionalized calphostin analogs as potent and selective inhibitors of protein kinase C (PKC)

As potential protein kinase C (PKC) inhibitors and photodynamic agents, the novel amino-functionalized calphostin analog 1,12-bis((benzoyl-amino)methyl)-3,10-perylenequinone was successfully prepared by dimerization of the key intermediate 3-(benzoylamino)methyl-1,2-naphthoquinone (9), which was synthesized by an efficient and relatively short synthetic sequence (eight steps) with satisfactory overall yield. The naturally occurring form of perylenequinone 12 was prepared by consecutive methylation and demethylation reactions. In our synthetic strategy, it was beneficial that the amino functionality of 1,2-naphthoquinone 9 could be easily introduced at an early synthetic stage and subsequently dimerized to prepare various potentially bioactive perylenequinones.