Novel phorbol analogs which bind to protein kinase C (PKC) without activation

13-Deacetoxy-11-demethyl-phorbol derivatives with acyl groups of various lengths (from hexanoyl to tetradecanoyl) at the C-12 position were synthesized in an optically active form. Although considerable binding affinities to PKC were observed by analogs 3-7, no activation of PKC was seen even at 10 microM.