The bis(enol triflate) route to dienediyne models of the biradical formingand DNA-cleaving natural product neocarzinostatin chromophore

The exceedingly cyctotoxic compound neocarzinostatin chromophore continues to fascinate chemists and biologists. Several groups have set out to synthe size this molecule and/or simplified functional analogues thereof. Pertinen t work of our groups is compiled in the following. As an entry to the Z-die nediyne systems we employed Cacchi couplings between the bis(enol triflates ) Z-34 or Z-35 and terminal alkynes. From there, we synthesized type-21 and type-22 dienediynes. They engaged in neocarzinostatin-type cyclo-aromatiza tions 23-->25 and 24-->26, respectively. In addition, we prepared dienediyn es of general structures 27 or 28. They were carried on to Saito-Myers cycl izations 29-->31 and 30-->32, respectively. 1 The Dienediyne Antitumor Agent Neocarzinostatin and its Mode of Action 2 Designing Dienediyne Mimics of the Chemistry of the Neocarzinostatin Chro mophore 3 Retrosynthetic Analysis and Syntheses of Simple 4 Dienediynes Syntheses and Cycloaromatizations of Bicyclic Dienediynes 4.1 5-/10- and 5-/11-Bicyclic Ring Systems 4.2 6-/10- and 6-/11-Bicyclic Ring Systems 5 Synthesis of Tricyclic Dienediynes 5.1 Dienediynes Containing Epoxide Rings 5.2 "Fully" Oxygenated Tricyclic Dienediynes from Bistriflates - Stretching our Approach too far?