title: A configurational switch based on iridium-catalyzed allylic cyclization: application in asymmetric total syntheses of prosopis, dendrobate, and spruce alkaloids.
abstract: A method for the stereoselective synthesis of 2,6-disubstituted piperidines has been developed that is based on the use of an intramolecular iridium-catalyzed allylic substitution as a configurational switch. The procedure allows the preparation of 2-vinylpiperidines with enantiomeric excesses (ee) of greater than 99%. As applications, total syntheses of piperidine alkaloids have been elaborated, most often by using Ru-catalyzed cross-metatheses as a key step for introduction of a side chain. Asymmetric total syntheses of the prosopis alkaloids (+)-prosopinine, (+)-prosophylline, (+)-prosopine, and of the dendrobate alkaloid (+)-241D and its C6 epimer are described.
authors.affiliation: Organisch-Chemisches Institut der Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Gnamm
authors.forename: Kerstin
authors.initials: K
authors.lastname: Brödner
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Krauter
authors.forename: Günter
authors.initials: G
authors.lastname: Helmchen
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D000498:Allyl Compounds / Q000737:chemistry; D000818:Animals; D001001:Anura; D002384:Catalysis; D003500:Cyclization; D007495:Iridium / Q000737:chemistry; D015394:Molecular Structure; D010880:Piperidines / Q000138:chemical synthesis* / Q000737:chemistry; D029862:Prosopis / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D000498:Allyl Compounds; D010880:Piperidines; C459240:prosophylline; D007495:Iridium; D012428:Ruthenium