title: A Lewis Acid Catalyzed annulation to 2,1-benzisoxazoles.
abstract: We report here a new, atom economical annulation to 2,1-benzisoxazole scaffolds via the BF3·Et2O-catalyzed reaction of glyoxylate esters and nitrosoarenes. The developed method represents a convergent route to this compound class from previously unexplored inputs and provides a range of 2,1-benzisoxazoles in moderate to high yields under convenient conditions. Along with exploration of substrate scope, initial mechanistic investigation through (18)O labeling and the synthesis of a reaction intermediate provides evidence for an unusual umpolung addition of glyoxylates to nitrosobenzenes with high O-selectivity, followed by a new type of Friedel-Crafts cyclization.
authors.affiliation: Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520-8107, United States.
authors.forename: Kate D
authors.initials: KD
authors.lastname: Otley
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Ellman
mesh_terms: D002384:Catalysis; D003500:Cyclization; D007555:Isoxazoles / Q000138:chemical synthesis* / Q000737:chemistry; D058116:Lewis Acids / Q000737:chemistry*; D015394:Molecular Structure; D009603:Nitroso Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: C441200:1,2-benzisoxazole; D007555:Isoxazoles; D058116:Lewis Acids; D009603:Nitroso Compounds; C012456:nitrosobenzene