A new chiral bicyclic guanidine-catalyzed direct catalytic aldolreaction of 5H-oxazol-4-ones with aldehydes has been developed. The present aldolreaction proceeds smoothly with high enantioselectivity using bicyclic guanidines bearing a hydroxy group at the appropriate position, and various combinations of 5H-oxazol-4-ones and aldehydes are applicable. The method provides synthetically useful alpha
the presence of an L-tert-leucine-derived urea–ammonium salt as phase-transfer catalyst, a highly enantioselective alkylation of 5H-oxazol-4-ones with various benzyl bromides and allylic bromides has been developed to furnish catalytic asymmetric synthesis of biologically important dialkylated α-hydroxy carboxylic acids with a broad scope. This is the first example of an L-amino acid-derived urea–ammonium
Highly diastereoselective and enantioselective Michael addition of 5H-oxazol-4-ones to α,β-unsaturated ketones catalyzed by a new bifunctional organocatalyst with broad substrate scope and applicability
作者:Huicai Huang、Kailong Zhu、Wenbin Wu、Zhichao Jin、Jinxing Ye
DOI:10.1039/c1cc15928c
日期:——
A new thiourea-tertiary amine bifunctional catalyst derived from L-tert-leucine was developed and provides excellent stereocontrol in a novel and direct Michaeladdition of 5H-oxazol-4-ones to alpha,beta-unsaturated ketones with much broad substrate scope. The conjugate addition products with chiral vicinal quaternary and tertiary stereocenters can be easily transformed to structurally interesting
Non-hydrogen bond catalyst-mediated diastereoselective conjugate additions of 5<i>H</i>-oxazol-4-ones to <i>o</i>-hydroxyphenyl-substituted <i>p</i>-quinone methides
作者:Ziyang Wang、Anqi Huang、Fang Fang、Pengfei Li、Guokai Liu、Wenjun Li
DOI:10.1039/d0ob01558j
日期:——
An efficient DBU-catalyzed conjugateaddition of 5H-oxazol-4-ones to o-hydroxyphenyl-substituted p-quinone methides has been developed, affording the valuable diarylmethanes in high yields with excellent diastereoselectivity. This strategy demonstrates a robust access to a wide range of diarylmethane derivatives possessing biologically significant o-hydroxyphenol and p-hydroxyphenol moieties under
Highly enantioselective allylic alkylation of 5 H -oxazol-4-ones with Morita-Baylis-Hillman carbonates
作者:Han Xu、Feng Sha、Xin-Yan Wu
DOI:10.1016/j.tet.2018.06.055
日期:2018.8
An organocatalytic enantioselectiveallylicalkylation of 5H-oxazol-4-ones with Morita-Baylis-Hillman carbonates has been developed. With 10 mol% of commercially available cinchonidine, a wide range of substituted 5H-oxazol-4-one derivatives were constructed in good-to-excellent yields with high diastereo- and enantioselectivities. The allylicalkylation adducts obtained are valuable precursors for