Synthesis and properties of cyclohepta[de]naphthalene-7,8-dione, o-pleiadienequinone
Abstract
Cyclohepta[de]naphthalene-7,8-dione, o-pleiadienequinone (2), was synthesized by hydrolysis of the acenaphthylene–dichloroketene adduct (5); chloro(hydroxy)ketone (6) was the precursor. Compound (2) afforded the triacetate (16) by a Thiele–Winter-type reaction and a phenalene compound (19) by alkaline hydrolysis. Spectral data suggest that the dione (2) has contributions from such canonical forms as 2,3-(2a) and/or 4,5-benzotropolonate (2b) structures. The polarographic E½ value of the dione (2) is –0.23 V at pH 5.28 which is between that of 1,2-naphthoquinone and anthraquinone.