Diels-Alder reaction Grob fragmentation

In the laboratory of J.D. Winkler, the synthesis of the carbon framework of the eleutherobin aglycon was developed using a tandem Diels-Alder reaction and a Grob fragmentation as key steps.The tricyclic fragmentation precursor was subjected to potassium carbonate in DMF at 75 °C to afford the fragmentation product in 68% yield via a dianion intermediate that underwent a spontaneous hemiketalization. 

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