title: Isoxazole-embedded allylic zinc reagent for the diastereoselective preparation of highly functionalized aldol-type derivatives bearing a stereocontrolled quaternary center.
abstract: Highly functionalized aldol-type products bearing a β-quaternary center and a stereoselectively controlled γ-hydroxy function are readily prepared by the diastereoselective addition of an allylic zinc reagent embedded in an isoxazole ring to various aromatic and heteroaromatic aldehydes, in the presence of Lewis acids, such as MgCl2 or LaCl3⋅2 LiCl. After reductive cleavage of the N-O bond by using Fe, NH4Cl, aldol-type products bearing a stereocontrolled β-quaternary center and a γ-hydroxy group were observed. The benzylic reactivity of the isoxazolylmethylzinc reagent towards other electrophiles, such as acid chlorides, aryl and allylic halides, as well as aldehydes in the presence of BF3⋅OEt2 are also described.
authors.affiliation: Department Chemie und Biochemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München (Germany), Fax: (+49) 89-2180-77680.
authors.forename: Lydia
authors.initials: L
authors.lastname: Klier
authors.forename: Coura R
authors.initials: CR
authors.lastname: Diène
authors.forename: Manuel
authors.initials: M
authors.lastname: Schickinger
authors.forename: Albrecht
authors.initials: A
authors.lastname: Metzger
authors.forename: Andreas J
authors.initials: AJ
authors.lastname: Wagner
authors.forename: Konstantin
authors.initials: K
authors.lastname: Karaghiosoff
authors.forename: Ilan
authors.initials: I
authors.lastname: Marek
authors.forename: Paul
authors.initials: P
authors.lastname: Knochel
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D007202:Indicators and Reagents; D007555:Isoxazoles / Q000737:chemistry*; D058116:Lewis Acids / Q000737:chemistry; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry; D013237:Stereoisomerism; D015032:Zinc / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D007202:Indicators and Reagents; D007555:Isoxazoles; D058116:Lewis Acids; D009942:Organometallic Compounds; C116609:3-hydroxybutanal; D015032:Zinc
keywords: Lewis acids; isoxazoles; magnesium; quaternary centre; zinc