Indenone Chemistry. 4. Synthesis of Substituted 1-Naphthalenols and 8-Oxoindenopyrroles: Mechanism of an Indenone-Naphthalenol Rearrangement

Article abstract of DOI:10.1021/jo01305a016

Treatment of 2,3-bis(bromomethyl)-6-methoxy-1-indenone (1) with various nucleophiles constitutes a one-step synthesis of 2,4-disubstituted 1-naphthalenols 3.The mechanism of this reaction has been explored.This study reveals the intermediacy of 3-(bromomethyl)-6-methoxy-2-methylene-1-indanones of type 7, which are thought to be formed by a S_N2' substitution on the allylic bromide system of 1.A second nucleophilic attack on 7 leads to cyclopropinden-6-ones 9 via a homo S_N2' substitution.The latter rearrange spontaneously into the 1-naphthalenols 3.With carefully controlled reaction conditions an intermediate of type 7 could be isolated; it has been used in separate experiments with other nucleophiles.Depending on the nucleophile, this leads either to naphthalenols 3 or to 8-oxoindeno<1,2-c>pyrrolidines 5.