title: Asymmetric catalytic [4 + 1] annulations catalyzed by quinidine: enantioselective synthesis of multi-functionalized isoxazoline N-oxides.
abstract: A highly regio-, chemo-, diastereo- and enantioselective organocatalytic [4 + 1] annulation of 2-halo-1,3-dicarbonyl compounds with Morita-Baylis-Hillman adducts catalyzed by commercially available, low cost quinidine for the preparation of synthetically unique and medicinally multi-functionalized isoxazoline N-oxides with three stereogenic centers including adjacent quaternary and tertiary stereocenters has been developed. Notably, the unexpected product ethyl 2-((tert-butyldimethylsilyl)oxy)-2-(5,5-diacetyl-3-((methylsulfonyl)oxy)-4-phenylisoxazolidin-3-yl)acetate (8) bearing a quaternary stereocenter and two tertiary stereocenters was obtained from the undocumented 5,5-diacetyl-3-(2-ethoxy-1-hydroxy-2-oxoethyl)-4-phenyl-4,5-dihydroisoxazole 2-oxide (4ba).
authors.affiliation: Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Department of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, PR of China.
authors.forename: Zhi-Wei
authors.initials: ZW
authors.lastname: Guo
authors.forename: Jian-Wu
authors.initials: JW
authors.lastname: Xie
authors.forename: Ce
authors.initials: C
authors.lastname: Chen
authors.forename: Wei-Dong
authors.initials: WD
authors.lastname: Zhu
mesh_terms: D002384:Catalysis; D007555:Isoxazoles / Q000138:chemical synthesis / Q000737:chemistry*; D008958:Models, Molecular; D010087:Oxides / Q000138:chemical synthesis / Q000737:chemistry*; D011802:Quinidine / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D007555:Isoxazoles; D010087:Oxides; D011802:Quinidine