作者:Alemayehu Gashaw Woldegiorgis、Zhao Han、Xufeng Lin
DOI:10.1002/adsc.202101011
日期:2022.1.18
An enantioselective synthesis of unnatural pyrazole-based α-chiral amino acidderivatives from the asymmetric reaction of N-aryl-5-aminopyrazoles with β,γ-alkynyl-α-imino esters using a chiral spirocyclic phosphoric acid catalyst was developed. Using the established methodology, various pyrazole-based α-aminoacidderivatives with tetrasubstituted carbon stereocenters were obtained in 67–98% yields
An asymmetricorganocatalyticaza-Friedel-Craftsreaction was developed to give the enantioenriched Δ4-isoxazoline scaffold bearing a quaternary-substituted stereogenic centre in good-to-excellent yields and enantioselectivity (50–99%, 55–>99% ee). This protocol involves the in situ generated isoxazolium ions in the presence of a chiral phosphoric acid followed by the heteroarene addition through asymmetric
Photocatalytic Alkyl Addition to Access Quaternary Alkynyl α-Amino Esters
作者:Juyeong Kim、Jae Kyun Lee、Bongjin Moon、Ansoo Lee
DOI:10.1021/acs.orglett.2c03669
日期:2022.12.9
A regioselectivealkylation of β,γ-alkynyl-α-imino esters by visible-light photocatalysis has been developed. This method enables 1,2-addition of methyl, primary, secondary, and tertiary alkyl radicals to the conjugated imines under mild conditions to produce a variety of quaternary alkynyl α-amino acid and cyclic amino acid motifs. Alkyl radicals are generated from alkyl bis(catecholato)silicates
Divergent Synthesis of Isoxazolo[5,4‐<i>b</i>]pyridines
作者:Min Li、Wenzhe Li、Min Huang、Xiaomei Zhang
DOI:10.1002/ejoc.202301287
日期:2024.3
Tandem reactions of 5-aminoisoxazoles with β,γ-alkynyl-α-imino esters provided two types of isoxazolopyridines in moderate to good yields by using two different silver salts and a phosphoric acid as catalysts.
Biocatalytic deracemization of alkyl-2-hydroxy-4-arylbut-3-ynoates using whole cells of Candida parapsilosis ATCC 7330
作者:Thangavel Saravanan、Anju Chadha
DOI:10.1016/j.tetasy.2010.11.021
日期:2010.12
Racemic alkyl-2-hydroxy-4-arylbut-3-ynoates were deracemized to the (S)-alky1-2-hydroxy-4-arylbut-3-ynoates in excellent enantiomeric excesses (up to >99%) and good isolated yields (up to 81%) with the biocatalyst Candida parapsilosis ATCC 7330. The absolute configuration of the resulting enantiomer was assigned by H-1 NMR using Mosher's method. (C) 2010 Elsevier Ltd. All rights reserved.