title: Efficient synthesis of tricyclic benzobisoxazines by silica gel catalysis.
abstract: A new method for the synthesis of tricyclic benzobisoxazines, based upon silica gel-catalyzed formation of two 3,1-oxazine rings, is reported. The reversibility of the condensation reaction, forming an oxazine ring, allows for implementation of silica gel catalyzed ketone exchange in benzobisoxazine, thus enabling access to nonsymmetric derivatives of benzobisoxazines.
authors.affiliation: Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, USA.
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Spagnol
authors.forename: Andrzej
authors.initials: A
authors.lastname: Rajca
authors.forename: Suchada
authors.initials: S
authors.lastname: Rajca
mesh_terms: D000447:Aldehydes / Q000737:chemistry; D048588:Benzoxazines / Q000138:chemical synthesis*; D002384:Catalysis; D002855:Chromatography, Thin Layer; D007659:Ketones / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D048588:Benzoxazines; D007659:Ketones; D058428:Silica Gel; D012822:Silicon Dioxide