SYNTHETIC STUDIES ON THE COMPOUNDS RELATED TO NEOCARZINOSTATIN CHROMOPHORE .2. SYNTHESIS OF THE OPEN-CHAIN (E)-DIENEDIYNE AND (Z)-DIENEDIYNE SYSTEMS AND ITS APPLICATION TO THE SYNTHESIS OF A STRAIN-RELEASED CYCLIC ANALOG

The "double coupling" reaction of the (E)- and (Z)-dienol ditriflates (5 and 6) with various propargyl alcohols was found to give the (E)- and (Z)-dienediyne diols, the open-chain analogues of neocarzinostatin chromophore, stereospecifically. Those (E)- and (Z)-dienediyne diols exhibited comparable cytotoxicity against P388 murine leukemia. The "single coupling" reaction of 6 took place preferentially at the exo-cyclic position to give the mono enol triflate, which could be further elaborated to dienediyne compounds by second coupling reaction with acetylenes. Application of this synthetic scheme could afford the novel and strain-released cyclic dienediyne acetal (33).