STUDIES IN THE CYCLOPROPARENE SERIES - OXYGEN-CONTAINING 1H-CYCLOPROPA[B]NAPHTHALENES AND THEIR METHYLIDENE DERIVATIVES

3,6-Dimethoxy-1H-cyclopropa[b]naphthalene 4 is available from 1,4-benz oquinone in four steps in 27-28% overall yield, The diether 4 provides a range of methylidene derivatives 15a-e by way of the disilyl compou nd 14, and is efficiently demethylated by cerium(IV) ammonium nitrate to provide 1H-cyclopropa[b]naphthalene-3,6-dione 16 (85%) whose crysta l structure is reported, Quinone 16 is the first stable cyclopropaquin one but it resists conversion into a I-C exocyclic olefin. The chemist ry of the compounds is described, their spectral data are discussed, a nd the cyclic voltammetry of 16 is provided.