o-Pleiadienequinones. Part 2. Nucleophilic substitution reaction of o-pleiadienequinone with alcohols

Abstract

In the course of the synthesis of the title compound (5) by the hydrolysis of the dichloro ketone (2) the acetoxy chloro ketone (6) was formed and accounted for in terms of the unusual bridgehead cation (3b). The nucleophilic substitution reaction of the compound (5) with various alcohols afforded alkoxy quinones (8) and/or acetals (7). The mechanism of the formation is discussed. The full characterization of 1-, 3-, and 6-methoxy quinones (8a₁), (8a₂), and (8a₃) by spectroscopic and electrochemical methods is described. An attempt to effect the de-O-methylation of the methoxy quinones (8a), by the action of trimethylsilyl iodide, failed; dihydro quinones (15a), (15b), and (15c) resulted. The oxidative rearrangement of compound (5) to γ-lactone (17) in the reaction with iron(III) sulphate is described.