title: α-Crotyl-α-difluoroboranyloxy-amides: Structure and Reactivity of Isolable Intermediates in Stereospecific α-Ketol Rearrangements.
abstract: The stereospecific BF3-mediated α-ketol rearrangement of β-hydroxy-α-ketoamides yields isolable 2-difluoroboranyloxy-3-keto-amides. X-ray and NMR analysis reveal a carbonyl coordination of the boron by the amide not the ketone. The boron complexes are air-stable solids, can be purified by silica gel chromatography, and exhibit novel reactivity in bromination and superior stereoselectivity in dipolar cycloaddition reactions.
authors.affiliation: Fachbereich Chemie, Philipps-University Marburg, Hans-Meerwein-Strasse 4, D-35043 Marburg, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Rossbach
authors.affiliation: Fachbereich Chemie, Philipps-University Marburg, Hans-Meerwein-Strasse 4, D-35043 Marburg, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Harms
authors.affiliation: Fachbereich Chemie, Philipps-University Marburg, Hans-Meerwein-Strasse 4, D-35043 Marburg, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Koert
mesh_terms: D000577:Amides / Q000138:chemical synthesis* / Q000737:chemistry; D001896:Boron Compounds / Q000737:chemistry*; D061565:Cycloaddition Reaction; D054879:Halogenation; D007659:Ketones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D000577:Amides; D001896:Boron Compounds; D007659:Ketones; C520957:beta-ketoamide