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Intramolecular 1,3-dipolar cycloaddition of unsaturated nitrones derived from methyl α-d-glucopyranoside |
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| Authors: | Petra Pá dá r,Pé ter Forgó ,Gá bor Paragi,Lajos Ková cs |
| Affiliation: | a Department of Medicinal Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary b Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary c Protein Chemistry Research Group, Hungarian Academy of Sciences, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary d Chemistry, School of Engineering and Physical Sciences, William H. Perkin Building, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, UK |
| Abstract: | The intramolecular 1,3-dipolar cycloaddition of unsaturated nitrones derived from methyl α-d-glucopyranoside with 2-furaldehyde has been studied. This cycloaddition was found to afford three 9-oxa-1-azabicyclo[4.2.1]nonane diastereomers in a 3:1:1 ratio [with the principal isomer possessing a (3S,4R,5S,6S,8S) configuration, determined by NMR spectroscopy]. The effects of different Lewis acid catalysts (MgCl2, ZnCl2 and BF3·OEt2) on yields and diastereomeric ratios have been examined in detail. The best result (90% yield) was achieved when MgCl2 was present (in toluene, 120 °C bath temperature, 12 h). The stereoselectivity of the 1,3-dipolar cycloaddition was not significantly altered under the conditions investigated. |
| Keywords: | 1,3-Dipolar cycloaddition Isoxazolidines Bicyclic 1,2-oxazepanes 9-Oxa-1-azabicyclo[4.2.1]nonanes Asymmetric synthesis |
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