REACTIVITY OF THE 5-HYDROACENAPHTHYLENE ANION TOWARDS ELECTROPHILES

The dianion of acenaphthylene can be converted into the 5-hydroanion b y protonation with one equivalent of methanol. Subsequent reaction wit h electrophiles such as allyl bromide and propargyl bromide occurs sel ectively at position 1, resulting in the formation of the novel 1-ally lacenaphthene and 1-propargylacenaphthene. In addition to what was obs erved in the case of methyl iodide, the hitherto unknown 1,1-dialkylat ed acenaphthene derivatives are formed as minor products; probably the lower reactivity of the unsaturated bromides is responsible for this side reaction. From the products of the reactions with 3,3-dimethylall yl bromide and (bromomethyl)cyclopropane the mechanism was found to be S(N)2. Reaction of the hydroanion with benzyl bromide takes place at position 1 as well as at position 2a. The reactivity of carbon 2a towa rds the soft electrophile benzyl bromide is attributed to the high HOM O coefficient at this position.