A highly efficient strategy for the kinetic resolution of Michael adducts was realized using a chiral N‐heterocyclic carbene catalyst. The kinetic resolution provides a new convenient route to single diastereomers of cyclohexenes and Michael adducts in good yields with high enantiomeric excesses (up to 99 % ee with a selectivity factor of up to 458). This “two flies with one swat” concept allows the
Enantioselective Michael addition of malononitrile to chalcones catalyzed by a simple quinine–Al(OiPr)3 complex: a simple method for the synthesis of a chiral 4H-pyran derivative
Enantioselective Michael addition of malononitrile to chalcones was catalyzed by a simple quinine and Al(O(i)Pr)(3) complex and products were obtained in good ee as well as high yields, which facilitated the asymmetric synthesis of a biologicallyactive 4H-pyran compound.
A complementary pair of enantioselective switchable organocatalysts
作者:Guillaume De Bo、David A. Leigh、Charlie T. McTernan、Shoufeng Wang
DOI:10.1039/c7sc02462b
日期:——
A pair of enantioselective switchable bifunctional catalysts are shown to promote a range of conjugate addition reactions in up to 95:5 e.r. and 95% conversion. Each catalyst can be switched OFF using conditions that switch the other catalyst ON. Catalyst ON:OFF ratios of up to 98:2 and 1:99 were achieved, with a ratio of reaction rates of up to 16:1 between the ON and OFF states, maintained over complete
An efficient and convenient highly enantioselective Michaeladdition of malononitrile to enones has been developed by using quinine as the organocatalyst. The adducts were isolated in excellent yield and high asymmetric induction (up to 95% ee). An easy route to difficultly accessible ester derivatives has been also disclosed.
Squaramide-catalyzed enantioselective Michael addition of malononitrile to chalcones
作者:Wen Yang、Yang Jia、Da-Ming Du
DOI:10.1039/c1ob06302b
日期:——
A highlyenantioselective Michael addition of malononitrile to chalconescatalyzed by a chiral quinine-derived squaramide catalyst has been developed. This organocatalytic reaction at a very lowcatalystloading (0.5 mol%) led to chiral γ-cyano carbonyl compounds in good yields with high enantioselectivities (up to 96% ee) under mild reaction conditions.