Asymmetric induction in nitrile oxide cycloadditions to optically active acrylates. Comparisons of acrylate conformations in thermal and acid-catalyzed 1,3-dipolar and Diels-Alder cycloaddition transition states
Highly Stereoselective [3+2] Cycloadditions of Nitrile Oxides to Methyl 4-<i>O</i>-Acryloyl-6-deoxy-2,3-<i>O</i>-(<i>t</i>-butyldimethylsilyl)-α-<scp>d</scp>-glucopyranoside
The [3+2] cycloadditions of benzonitrile oxide or pivalonitrile oxide to methyl 4-O-acryloyl-6-deoxy-2,3-di-O-(t-butyldimethylsilyl)-α-d-glucopyranoside provided the respective adducts, each as virtually a single diastereomer. By reductive removal of the carbohydrate template from each adduct, the respective (R)-enriched Î2-isoxazoline derivative was obtained.
Asymmetric 1,3-Dipolar Cycloaddition of Nitrile Oxides Generated in situ by Direct Oxidation of Aldoximes
作者:Masamichi Tsuji、Yutaka Ukaji、Katsuhiko Inomata
DOI:10.1246/cl.2002.1112
日期:2002.11
The asymmetric1,3-dipolarcycloaddition of nitrileoxides, generated in situ from aldoximes by direct oxidation with tert-butyl hypochlorite, to 2-propen-1-ol was achieved by utilizing diisopropyl (R,R)-tartrate as a chiralauxiliary to afford the corresponding (R)-2-isoxazolines with high enantioselectivity up to 96% ee.
Enantioselective Synthesis of 2-Isoxazolines<i>via</i>Asymmetric 1,3-Dipolar Cycloaddition of Nitrile Oxide to Achiral Allyl Alcohol
作者:Yutaka Ukaji、Kazunori Sada、Katsuhiko Inomata
DOI:10.1246/cl.1993.1847
日期:1993.11
The asymmetric 1,3-dipolarcycloaddition of a nitrile oxide to an achiral allyl alcohol was achieved by the use of (R,R)-diisopropyl tartrate as a chiralauxiliary. Treatment of the allyl alcohol with diethylzinc and the tartrate, followed by the addition of diethylzinc and a hydroximoyl chloride, afforded the corresponding (R)-2-isoxazolines with excellent enantioselectivity.
Catalytic Asymmetric 1,3-Dipolar Cycloaddition of Nitrile Oxides to an Achiral Allyl Alcohol Utilizing Diisopropyl Tartrate as a Chiral Auxiliary
作者:Makoto Shimizu、Yutaka Ukaji、Katsuhiko Inomata
DOI:10.1246/cl.1996.455
日期:1996.6
The catalyticasymmetric 1,3-dipolar cycloaddition of nitrile oxides to an achiral allyl alcohol was achieved by the use of a catalytic amount of diisopropyl (R,R)-tartrate as a chiral auxiliary to afford the corresponding (R)-2-isoxazolines with high enantioselectivity. In order to realize reproducible higher stereoselection, the addition of a small amount of ethereal compound such as 1,4-dioxane
The preparation of optically active δ2- isoxazolines. A model for asymmetric induction in the non lewis acid catalyzed reactions of oppolzer's chiral sultam
作者:Dennis P Curran、Byeang Hyean Kim、James Daugherty、Timothy A Heffner
DOI:10.1016/0040-4039(88)85291-2
日期:1988.1
Good diastereoselectivity (ca. ) is reported in the cycloaddition reactions of Oppolzer'schiralsultam with nitrile oxides. A model is proposed which may apply to other nonLewisacid promoted reactions of this sultam.