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3,4-Dihydrocoumarin derivatives have demonstrated promising biological activities as natural products and pharmaceuticals.Therefore,much attention has been paid on the development of efficient approaches for the construction and decoration of this scaffold.In 2009,Ye and co-workers reported the N-Heterocyclic Carbene (NHC)-catalyzed cycloaddition of ketenes and o-quinone methides to fabricate dihydrocoumarin.Carboxylic acids are easily available and inexpensive,which makes them excellent feedstocks for organic syntheses.The generation of NHC-bounded enolate and homoenolate from carboxylic acids via in situ activation was developed by Scheidt et al and our group,respectively.Thus we envisioned that the NHC-catalyzed enantioselective[4+2]annulation of saturated carboxylic acids and o-quinone methides could pave a new avenue to dihydrocoumarin through in situ activation.