ORGN 678

We report the biomimetic design and synthesis of pentathiabenzocycloheptene-1,2-diol (1) and related dimeric tetraols by incorporation of inorganic polysulfane H₂S_x (x>1) into o-quinone by a 1,6-conjugate addition process. Aromaticity can be considered as the driving force in the reaction. The second addition of sulfur then takes place, namely the oxidation of 3-mercapto- or polysulfido-benzene-1,2-diol (2) to form compound 1. Density functional theory and semiempirical calculations are described that predict a biosynthetic pathway of the natural product polysulfanes lissoclinotoxin A, D, and F from reduced elemental sulfur and dopamine-o-quinone. The natural polysulfanes have been previously isolated from a marine tunicate by C. Ireland, M. Namikoshi, D. J. Faulkner, T. Molinski, and others.