Unmatched-Electron-Demand Diels-Alder Reaction of Lindenane-Based Electron-Deficient Trienes.

An unmatched-electron-demand Diels-Alder reaction (UMEDDA) between lindenane-based electron-deficient dienes and electron-deficient dienophiles has been developed. The electron-withdrawing group on the dienophile can be extended to ketones, aldehydes, esters, amides, benzoquinones, and glyoxylates, producing [4 + 2] cycloadducts with excellent stereoselectivity and regioselectivity. DFT calculations are conducted to elucidate its regioselectivity, stereoselectivity, and electronic-effect-dependent reactivity. This work contributes to clarifying the generality of UMEDDA reactions and proves the extendable potential of this reaction in the related pharmaceutical research and total synthesis of complex organic molecules.