Reactivity umpolung of the cycloheptatriene core in hexa(methoxycarbonyl)cycloheptatriene.

A reactivity umpolung approach for the derivatization of cycloheptatrienes was extended to hexa(methoxycarbonyl)cycloheptatriene, which forms the corresponding anion reactive towards electrophiles. Despite the presence of four potential reactive sites, the reactions mainly involve the initial electrophilic attack onto the α-position relative to the hydrogen atom. The selectivity is either due to the high stability of the α-nucleophilic conformer or due to the promotion by the adjacent ester group. Cascade reactions upon the target connection, if installed, include the formation of norcaradienes, dihydroindazoles, a tetracyclodecene and a hydrazonocycloheptatriene derivative.