Naphthoquinones of great structural variety are widespread among living organisms. 2-Hydroxy-I ,4-naphthoquinone (lawsone, I ) is found in the leaves of various species of Lawsonia and is used for hair dyeing"; recently, it served as starting material for the synthesis of several derivatives exhibiting potent cytotoxic activity'! We were interested to investigate the possibility of formation of 1,4-naphthoquinone derivatives by a new route involving reactions of its iodonium ylide, i.e. 3-(phenyliodonio)-l,2,4-trioxo-l,2,3,4tetrahydronaphthalenide (3). The structural features of I suggested that it should form 3 upon treatment with (diacet-0xyiodo)benzene 2. We report here that 3 is indeed formed readily and represents a new kind of an iodonium ylide since its ylidic C is flanked by two carbonyl groups, one of which is adjacent to another carbonyl. Some reactions of 3 will serve to illustrate its potency and also its difference in reactivity compared to other iodonium ylides. When 1 was treated in the standard way3) with 2 in aqueous methanolic KOH at -5"C, it gave 3 in 80% yield. The yield was improved to 92% when the use of alkali was omitted and the reaction was carried out in chloroform at O'C. It appears that &OH + Phl(OAc)2 --+ -2 AcOH 0 1 2 I 3