component system comprising of a primary β-amino silyl ethers as an organocatalyst and N-protected amino acids as a co-catalyst put together worked as an efficient organocatalyst system in the heteroDiels–Alderreaction of isatins with enones affording the chiral spirooxindole-tetrahydropyranones in good chemical yields and stereoselectivities (up to 94%, up to dr 78:22., up to 85% ee).
First asymmetric cascade reaction catalysed by chiral primary aminoalcohols
作者:Carlos Arróniz、Carmen Escolano、F. Javier Luque、Joan Bosch、Mercedes Amat
DOI:10.1039/c1ob05400g
日期:——
Readily available chiral primary 1,2-aminoalcohols and diamines have been explored as organocatalysts for a domino Michael–aldol reaction. Their application in this organocascade process afforded cyclohexanone A with high levels of reactivity (up to 91% yield) and stereoselectivity (>97 : 3 d.r., up to 93% ee). Depending on the acid cocatalyst different chiral species (cyclic secondary aminesvs. acyclic primary amines) might catalyse the process. In order to shed light on the catalytic activation, several experiments were carried out and a detailed possible reaction mechanism is proposed. Theoretical studies support the stereochemical outcome of the process.