title: Synthesis of prenyl- and geranyl-substituted carbazole alkaloids by DIBAL-H promoted reductive pyran ring opening of dialkylpyrano[3,2-a]carbazoles.
abstract: The DIBAL-H promoted reductive pyran ring opening of dialkylpyrano[3,2-a]carbazoles provides a direct access to a broad range of prenyl- and geranyl-substituted carbazoles. Formation of a pyran ring followed by reductive ring opening represents a new method for the introduction of prenyl and geranyl groups. In the course of the present work, we achieved the first total syntheses of the following eight carbazole alkaloids: clauraila-E, 7-hydroxyheptaphylline, 7-methoxyheptaphylline, mukoenine-B (clausenatine-A), mukoenine-A (girinimbilol), mahanimbinol (mahanimbilol), euchrestine-A, and isomurrayafoline-B.
authors.affiliation: Department of Chemistry, Technische Universität Dresden, Bergstraße 66, 01069 Dresden (Germany), Fax: (+49) 351-463-37030 http://www.chm.tu-dresden.de/oc2/
authors.forename: Ronny
authors.initials: R
authors.lastname: Hesse
authors.forename: Olga
authors.initials: O
authors.lastname: Kataeva
authors.forename: Arndt W
authors.initials: AW
authors.lastname: Schmidt
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Knölker
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D002227:Carbazoles / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D054876:Prenylation; D011714:Pyrans / Q000737:chemistry; D019163:Reducing Agents / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D002227:Carbazoles; D009942:Organometallic Compounds; D011714:Pyrans; D019163:Reducing Agents; C041514:carbazole; C035719:diisobutylaluminum
keywords: CH bond activation; alkaloids; natural products; palladium; reduction