Diphenylprolinol silyl ether was found to be an effective organocatalyst in the enantioselective and direct Michael reaction of nitroethanol and α,β-unsaturatedaldehydes, affording the 1-hydroxy-trans-3,4-disubstituted tetrahydropyrans after isomerization. The generated Michael addition products are useful synthetic intermediates, which can be converted into chiral tetrahydropyran with a quaternary
Multicomponent Synthesis of Cyclic Depsipeptide Mimics by Ugi Reaction Including Cyclic Hemiacetals Derived from Asymmetric Organocatalysis
作者:Alexander F. de la Torre、Daniel G. Rivera、Odette Concepción、Radell Echemendia、Arlene G. Correa、Márcio W. Paixão
DOI:10.1021/acs.joc.5b02158
日期:2016.2.5
The synthesis of novel cyclic depsipeptide mimics by means of an organocatalytic conjugate addition, leading to chiral cyclic hemiacetals, followed by a multicomponent reaction with α-amino acids and isocyanides, is described. The initial organocatalytic step is employed for the asymmetricderivatization of α,β-unsaturated aldehydes to 4,5-disubstituted 2-hydroxytetrahydropyrans, which are next used