title: A concise stereoselective route to the indoline spiroaminal framework of neoxaline and oxaline.
abstract: The stereoselective synthesis of tetracyclic intermediate, the indoline spiroaminal 3 for neoxaline (1) and oxaline (2), has been accomplished. The key step of the stereoselective synthesis of 3 was the Lewis acid mediated transcyclization of 4 to the diaminal 18, and the tungstate-catalyzed oxidation of 18 to obtain the nitrone 19, which easily cyclizes to the indoline spiroaminal framework 3. [structure: see text]
authors.affiliation: Kitasato Institute for Life Sciences, School of Infection Control Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Sunazuka
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Shirahata
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tsuchiya
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Hirose
authors.forename: Ryuma
authors.initials: R
authors.lastname: Mori
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Harigaya
authors.forename: Isao
authors.initials: I
authors.lastname: Kuwajima
authors.forename: Satoshi
authors.initials: S
authors.lastname: Omura
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D007093:Imidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D007202:Indicators and Reagents; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D007093:Imidazoles; D007202:Indicators and Reagents; D007211:Indoles; C490207:oxaline; C057812:indoline; C022264:neoxaline