An efficient three-step synthesis for benzotropolones via three catalytic steps is presented. Pyrogallol phenones are formed in the first step starting from pyrogallol, which is acylated by proton-catalysis. Catalytic hydrogenation of the phenones yields the corresponding alkylated pyrogallyl dervatives. In the final enzyme-catalyzed step the pyrogallol derivatives are annulated to form the benzotropolone cores. An alternative pathway via the ...
