DEMETHYL(TRIFLUOROMETHYL)ACTINOMYCINS .2. BIS(TRIFLUOROMETHYLATED) 4-(2'-BENZOXAZOLYL)ACTINOCIN DERIVATIVES

In a previous study, performed in connection with the total synthesis of trifluoromethylated actinocinyl peptides 2a, the oxidative condensa tion of the corresponding o-aminophenol precursor 1 furnished a novel trimerisation product, which had been tentatively assigned to the trip henedioxazine structure 3(1). Now, an improved synthesis of the trimer and extensive 1- and 2D-NMR studies have resulted in a new, quite une xpected structure: the 4-(2'-benzoxazolyl)actinocin derivative 8a, whi ch replaces 3. Apparently, the quinone-sided CF3 group of an actinocin intermediate is unusually activated and reacts with a third o-aminoph enol unit. The modifications to the synthesis increase the overall yie ld of demethyl(trifluoromethyl) actinomycins by a factor of five.