Regio- and stereoselective synthesis of isoxazolidine derivatives by asymmetric 1,3-dipolar cycloaddition reaction of chiral nitrones with 1-propene-1,3-sultone
作者:Hong-Kui Zhang、Wing-Hong Chan、Albert W. M. Leeb、Wai-Yeung Wong
DOI:10.1002/jhet.5570450402
日期:2008.7
Asymmetric 1,3-dipolar cycloadditions of chiral nitrones to 1-propene-1,3-sultone (1) were investigated. Chiral nitrones 6a-e reacted with sultone 1 in toluene at 90 °C for 24-36 h to give the corresponding isoxazolidines in moderate yields with high regioselectivities and stereoselectivities. The diastereoselectivity of this reaction varied with the choice of dipolarophile and the steric demands of
(+)-Muscarine was synthesized from S-(−)-ethyl lactate in five steps with the application of a zinc-mediated allylation reaction in aqueous media. Reversal of chelation-control stereoselectivity wa...
Diastereoselective Construction of the 6-Oxa-2-azabicyclo[3.2.1]octane Scaffold from Chiral α-Hydroxyaldehyde Derivatives by the Aza-Prins Reaction
作者:Alejandro Mahía、Ramón Badorrey、José A. Gálvez、María D. Díaz-de-Villegas
DOI:10.1021/acs.joc.7b01291
日期:2017.8.4
7S)-7-[(benzyloxy)methyl]-2-tosyl-6-oxa-2-azabicyclo[3.2.1]octane in a highly diastereoselective manner through an unexpected intramolecular nucleophilic attack. Our work has opened a new route toward the asymmetric synthesis of 7-(alkyl or aryl)-6-oxa-2-azabicyclo[3.2.1]octane derivatives fromchiral α-hydroxyaldehyde derivatives in one step.
Stereoselective Direct Amine-Catalyzed Decarboxylative Aldol Addition
作者:Kerstin Rohr、Rainer Mahrwald
DOI:10.1021/ol200412r
日期:2011.4.1
A stereoselective decarboxylative aldol addition of beta- and alpha-keto acids in the presence of catalytic amounts of amines is described. By the optional deployment of chiral enolizable aldehydes an access to enantiopure configurative defined ketopentoses, ketohexoses, or ketoheptoses is given.
Formation and reaction of 2-metalated N-Boc-4,4-dimethyl-1,3-oxazolidines in the presence of (−)-sparteine: new chiral formyl anion equivalents
作者:Naoki Kise、Tadashi Urai、Jun-ichi Yoshida
DOI:10.1016/s0957-4166(98)00319-x
日期:1998.9
Lithiation of N-Boc-4,4-dimethyl-1,3-oxazolidine with s-BuLi and the following reaction with benzaldehyde was carried out in the presence of (-)-sparteine. The reaction was not diastereoselective (syn:anti=46:54), but each isomer of the adducts was obtained enantioselectively (syn: 90% ee, anti: 88% eel. Addition of MgBr2 to the reaction mixture increased the diastereoselectivity to syn:anti=90:10. (C) 1998 Elsevier Science Ltd. All rights reserved.