The Diels-Alder reactivity of 2-vinylindenes: synthesis of functionalized tetrahydrofluorenes

Functionalized tetrahydrofluorenes were synthesized using a normal electron-demand Diels-Alder cycloaddition reaction between 2-vinylindenes and various dienophiles. Electron rich 2-vinylindenes bearing methoxy groups at the 4- and 7- positions were accessed through their corresponding 2-indenylpivalates obtained using a Pt-catalyzed cycloisomerization reaction. DFT calculations were used to rationalize the observed regioselectivity in the Diels-Alder reaction, and the cycloadditions were extended to a 2-allenylindene substrate.

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