An Investigation of the Reaction Mechanism of the Bis-acylation of Aromatics with o-Phthaloyl Dichlorides: Regioselective Synthesis of Anthraquinones

摘要

In our previous studies on the template effect in the ortho-regioselective electrophilic acylation of metal phe-nolates we have reported simple and mild reaction conditions for preparing anthraquinones 5 via a one-pot bisacylation of aromatic substrates with o-phthaloyl dichlorides 1 (Scheme 1). On the basis of our synthetic and mechanistic studies we thought that the entire process could be easily accomplished due to the temporary loss of the electron-withdrawing effect of the carbonyl group of theketo acid chlorides 3 which were converted into the corresponding pseudochlorides 4 via a "ring-chain tautomerism" (3 = 4).