title: Stereospecific Oxidation of Diacetoxyheterobetulin with Ozone and Dimethyldioxirane.
abstract: Stereospecific oxidation of diacetoxyheterobetulin with ozone and dimethyldioxirane led to 3β,28-diacetoxy-18α,19βH-urs-20α,21α-epoxide with yields of 79% and 87%, respectively. Oxidation with ozone was not selective and gave two minor products containing 2lα-hydroxy-20(30)-ene and 21a-hydroxy-20β,28-epoxy-fragments in ring E. The structures of 3β,28-diacetoxy-18α,19βH-urs-20α,21α-epoxide and 3β-diacetoxy-21α-hydroxy-20β,28-epoxy-18α,19βH-ursane were confirmed by X-ray analysis for the first time.
authors.forename: El'mira F
authors.initials: EF
authors.lastname: Khusnutdinova
authors.forename: Natalya I
authors.initials: NI
authors.lastname: Medvedeva
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Kazakov
authors.forename: Olga S
authors.initials: OS
authors.lastname: Kukovinets
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Lobov
authors.forename: Kirill Yu
authors.initials: KY
authors.lastname: Suponitsky
authors.forename: Oxana B
authors.initials: OB
authors.lastname: Kazakov
mesh_terms: D004852:Epoxy Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry; D013237:Stereoisomerism; D014315:Triterpenes / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: C000611014:3beta,28-diacetoxy-18alpha,19betaH-urs-20alpha,21alpha-epoxide; D004852:Epoxy Compounds; D014315:Triterpenes; C000611017:diacetoxyheterobetulin; D010126:Ozone; C064455:dimethyldioxirane