A series of simple 4‐hydroxyprolinamides was synthesised and they were found to act as organocatalysts for the asymmetric conjugate addition of aldehydes to nitroolefins in excellent yields (98%), with complete diastereoselectivity (99:1, syn:anti) and enantioselectivity (98% ee for syn). Furthermore, the use of low catalyst loadings (5 mol%) and a low aldehyde molar excess (1.5 equivalents) were achieved
The asymmetric challenge! New camphor‐based prolinamides were designed, synthesized, and proven to be a highly efficient organocatalysts for asymmetricMichael reactions. Treatment of unmodified aldehydes with nitroalkenes in the presence of 5–10 mol % organocatalysts provided the desired Michael products in high chemical yields (up to 94 %) and high to excellent levels of diastereo‐ and enantioselectivities
Michael addition of carbonyl compounds to nitroolefins under the catalysis of new pyrrolidine-based bifunctional organocatalysts
作者:A. Castán、R. Badorrey、J. A. Gálvez、P. López-Ram-de-Víu、M. D. Díaz-de-Villegas
DOI:10.1039/c7ob02798b
日期:——
the asymmetric Michael addition of carbonyl compounds to nitroolefins have been synthesised from homoallylamines, which are easily obtained from (R)-glyceraldehyde as a chiral precursor. Under optimal reaction conditions, these bifunctional organocatalysts showed a high catalytic efficiency (almost quantitative yield in most cases) and stereoselectivity in the Michael addition reactions of a variety
This Letter described the synthesis of the first diarylprolinol silyl ether-derived bifunctional thiourea organocatalysts. The catalysts were applied to the asymmetricMichaeladdition of aldehydes to nitroalkenes to give the desired adducts in good yields (up to 99%) with excellent enantioselectivities (up to 99% ee) and excellent diastereoselectivities (up to 99:1). The spatial placement of C-4 substituent
Synthesis of new pyrrolidine-based organocatalysts and study of their use in the asymmetric Michael addition of aldehydes to nitroolefins
作者:Alejandro Castán、Ramón Badorrey、José A Gálvez、María D Díaz-de-Villegas
DOI:10.3762/bjoc.13.59
日期:——
pyrrolidine-based organocatalysts with a bulky substituent at C2 were synthesized from chiral imines derivedfrom (R)-glyceraldehyde acetonide by diastereoselective allylation followed by a sequential hydrozirconation/iodination reaction. The new compounds were found to be effective organocatalysts for the Michael addition of aldehydes to nitroolefins and enantioselectivities up to 85% ee were achieved