title: An enantioselective total synthesis of (+)-geissoschizine.
abstract: [formula: see text] A concise asymmetric synthesis of the indole alkaloid (+)-geissoschizine (1) has been completed. The synthesis features the highly diastereoselective vinylogous Mannich reaction of 3 with 4 to give 5, which is elaborated into the key tetracyclic intermediate 7 in two steps. Following the stereoselective introduction of the ethylidene moiety to give 9, reduction of the lactam and radical decarboxylation via an acyl selenide gave 12, which was converted into (+)-geissoschizine by formylation. The synthesis requires only 11 chemical operations and proceeds in an overall yield of 17%.
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas at Austin 78712, USA. sfmartin@mail.utexas.edu
authors.forename: S F
authors.initials: SF
authors.lastname: Martin
authors.forename: K X
authors.initials: KX
authors.lastname: Chen
authors.forename: C T
authors.initials: CT
authors.lastname: Eary
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis*; D002243:Carbolines / Q000138:chemical synthesis*; D003653:Decarboxylation; D008352:Mannich Bases; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D002243:Carbolines; D008352:Mannich Bases; C410326:geissoschizine