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The availability of enantiomerically enriched 1,3-dienyl substituted quaternary stereocenters is highly valuable for the synthesis of complex natural compounds. Despite great advances in the area of construction of alkenyl-substituted types, a general, practical catalytic system that works for enantioselective formation of 1,3-diene derivatives still remains to be developed. Herein, we disclose the first asymmetric Claisen rearrangement of allenyl vinyl ethers to access optically active β-ketoesters, containing branched 1,3-butadienyl substituted stereocenters. A variety of substrates bearing a range of useful functional groups were well tolerated, thus affording the corresponding products with excellent enantioselectivities (up to 99% ee) and high yields (up to 91%). [ABSTRACT FROM AUTHOR]

An asymmetric inverse-electron-demand hetero-Diels–Alder reaction between o-quinone methides and azlactones to generate potentially pharmacological active dihydrocoumarins has been achieved efficiently by using a chiral N,N′-dioxide–Sc(iii) complex as the catalyst. The desired products were obtained in high yields with excellent enantioselectivities and diastereoselectivities (up to 94% yield, 96% ee and ＞19 : 1 dr) under mild reaction conditions. A concerted reaction pathway was confirmed by Operando IR and control experiments. [ABSTRACT FROM AUTHOR]

A highly efficient catalytic asymmetric Diels-Alder reaction between 3-vinylindoles and methyleneindolinones has been achieved using chiral N,N'-dioxide-Ni(II) complexes as the catalysts. A wide variety of substrates were readily tolerated, generating exclusively the corresponding exo-carbazolespirooxindole derivatives in excellent yields with high enantiomeric excesses (up to 98% yield, >99 : 1 d.r., and 98% ee) under mild reaction conditions.