Stereoselective synthesis of medicinally relevant furo[2,3-d]pyrimidine framework by thermal rearrangement of spirocyclic barbiturates

摘要

A new rearrangement of functionalised cyclopropanes was found: the thermally initiated transformation of substituted 2-aryl-4,6,8-trioxo-5,7-diazaspiro[2.5]octanes in DMSO at 100 degrees C results in the formation of furo[2,3-d]pyrimidines in 50-75% yields. Similar results were obtained using [BMim][BF4] as a solvent. NMR and single-crystal X-ray diffraction analysis indicate stereoselective formation of (5R*, 6R*) isomers by thermal rearrangement of 2-aryl-1-cyano-5,7-dimethyl-4,6,8-trioxo-5,7-diazaspiro[2.5] octane-1-carboxylates.