Synthesis of Dialkyl 4-Ethoxy-2,5-dihydro-1-(9,10-dihydro-9,10-dioxoanthracen-1-yl)-5-oxo-1H-pyrrole2,3-dicarboxylates

Abstract

The reaction of ethyl 9,10-dihydro-9,10-dioxoanthracen-1-yl-carbamoyl-formate with dialkyl acetylenedicarboxylates in the presence of triphenylphosphine leads to dialkyl 4-ethoxy-2,5-dihydro-1-(9,10-dihydro-9,10-dioxoanthracen-1-yl)-5-oxo-1H-pyrrole-2,3-dicarboxylates in fairly good yields. A dynamic NMR effect is observed as a result of restricted rotation around the single bond linking the anthraquinone moiety and the heterocyclic ring system, which is attributed to the interaction between the pyrrole residue and the peri C═O group.

Keywords:

• Intramolecular Wittig reaction
• peri interaction
• restricted rotation
• triphenylphosphine