Effect of High Pressure on the Organocatalytic Asymmetric Michael Reaction: Highly Enantioselective Synthesis of γ-Nitroketones with Quaternary Stereogenic Centers
摘要:
The significant effect of hydrostatic pressure on the difficult organocatalytic 1,4-conjugate addition of nitroalkanes to prochiral sterically congested beta,beta-disubstituted enones is demonstrated. This approach allows for the synthesis of gamma-nitroketones containing quaternary stereogenic centers with good yields, excellent enantioselectivity, and low loading (1-5 mol %) of simple chiral primary amine catalysts.
A versatile approach to functionalized cyclic ketones bearing quaternary carbon stereocenters via organocatalytic asymmetric conjugate addition of nitroalkanes to cyclic β-substituted α,β-Enones
quaternary stereogeniccenters at β-C has been developed. This is an extension of the method that we developed during the total synthesis of (−)-haliclonin A, which features the employment of structurally relatively simple, cheap and easily available primary amine-thiourea derived from (R,R)-1,2-diaminocyclohexane as the chiral catalyst. The method shows wide substrate scope, good functional group tolerance
Effect of High Pressure on the Organocatalytic Asymmetric Michael Reaction: Highly Enantioselective Synthesis of γ-Nitroketones with Quaternary Stereogenic Centers
The significant effect of hydrostatic pressure on the difficult organocatalytic 1,4-conjugate addition of nitroalkanes to prochiral sterically congested beta,beta-disubstituted enones is demonstrated. This approach allows for the synthesis of gamma-nitroketones containing quaternary stereogenic centers with good yields, excellent enantioselectivity, and low loading (1-5 mol %) of simple chiral primary amine catalysts.