A remote β,γ-regioselective asymmetric inverse-electron-demand oxa-Diels–Alder reaction between allylic ketones and α-cyano-α,β-unsaturated ketones has been developed through induced extended dienamine catalysis of a cinchona-derived primary amine. A spectrum of densely substituted dihydropyran frameworks were efficiently produced with excellent enantioselectivity and fair to exclusive diastereoselectivity
An effective one-pot sequential Michael addition/deprotection/cyclization/tautomerization approach to N-unprotected fully substituted trans-2-pyrrolines has been developed.
Enantioselective synthesis of substituted pyrans via amine-catalyzed Michael addition and subsequent enolization/cyclisation
作者:Utpal Das、Chan-Hui Huang、Wenwei Lin
DOI:10.1039/c2cc31445b
日期:——
An organocatalytic construction of optically enriched substituted pyran derivatives via amine-catalyzed Michael addition and subsequent enolization/cyclisation has been described starting from electronically poor alkenes. Functionalized pyrans were obtained in high enantioselectivities (up to 96%) and good yields (up to 90%) having three contiguous chiral centers.
Double Thiol-Chiral Brønsted Base Catalysis: Asymmetric Cross Rauhut–Currier Reaction and Sequential [4 + 2] Annulation for Assembly of Different Activated Olefins
the intermolecular cross Rauhut-Currierreaction of 2-cyclopentenone and isatin-based alkylidene malononitriles. The resulting chiral adducts were sequentially assembled with diverse electron-deficient olefins to furnish highly enantioenriched cyclohexane derivatives (up to 96:4 er, >19:1 dr). A similar catalytic system of 2-mercaptobenzoic acid and quinine was further developed for the reaction of
DABCO-mediated [4 + 4] domino annulation reactions of ynones and α-cyano-α,β-unsaturated ketones were discovered. The domino process affords an alternative route to eight-membered cyclic ethers in good yields under mild conditions.