Synthesis of naphthoquinoles as potential antitumor agents related to jacaranone

Naphthoquinols 3a, 3b and 3c were synthesized from the corresponding naphthoquinones by the series of reactions, protection of one carbonyl with trimethylsilycyanide, reaction with the enolate of methyl acetate, and hydrolytic deprotection with aqueous silver fluoride. The unusual internal hemiketals 4a and 4b appeared to be byproducts of one of these reactions. These naphthoquinols, which are related to the antitumor compound jacaranone (1a), were tested for cytotoxicity and found to be inactive.