A Diels-Alder Approach to Anthrapyran Antibiotics

A new entry to the synthesis of anthrapyran antibiotics has been accomplished through the synthesis of a 4H-anthra[1,2-b]pyran-4,7,12-trione model. The key step features a Diels-Alder reaction between a substituted 5-vinyl-3,4-dihydro-2H-pyran and naphthoquinone as the dienophile. The resulting tetracyclic adduct is then processed towards the targeted trione in a few steps.