title: Isolation and Total Synthesis of Kirkamide, an Aminocyclitol from an Obligate Leaf Nodule Symbiont.
abstract: The new C7N aminocyclitol kirkamide (1) was isolated from leaf nodules of the plant Psychotria kirkii by using a genome-driven (1)H NMR-guided fractionation approach. The structure and absolute configuration were elucidated by HRMS, NMR, and single-crystal X-ray crystallography. An enantioselective total synthesis was developed, which delivered kirkamide (1) on a gram scale in 11 steps and features a Ferrier carbocyclization and a Pd-mediated hydroxymethylation. We propose that kirkamide is synthesized by Candidatus Burkholderia kirkii, the obligate leaf symbiont of Psychotria kirkii. Kirkamide (1) was shown to be toxic to aquatic arthropods and insects, thus suggesting that bacterial secondary metabolites play a protective role in the Psychotria/Burkholderia leaf nodule symbiosis.
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel (Switzerland).
authors.forename: Simon
authors.initials: S
authors.lastname: Sieber
authors.affiliation: Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, 8008 Zürich (Switzerland).
authors.forename: Aurélien
authors.initials: A
authors.lastname: Carlier
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel (Switzerland).
authors.forename: Markus
authors.initials: M
authors.lastname: Neuburger
authors.affiliation: Agroscope, Reckenholzstrasse 191, 8046 Zürich (Switzerland).
authors.forename: Giselher
authors.initials: G
authors.lastname: Grabenweger
authors.affiliation: Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, 8008 Zürich (Switzerland).
authors.forename: Leo
authors.initials: L
authors.lastname: Eberl
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel (Switzerland). karl.gademann@unibas.ch.
authors.forename: Karl
authors.initials: K
authors.lastname: Gademann
mesh_terms: D001688:Biological Products / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D019117:Burkholderia / Q000502:physiology; D018360:Crystallography, X-Ray; D054812:Cyclitols / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D003514:Cyclohexylamines / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D008745:Methylation; D008958:Models, Molecular; D010165:Palladium / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry / Q000382:microbiology; D032069:Psychotria / Q000737:chemistry* / Q000382:microbiology; D013559:Symbiosis
chemical_list: D001688:Biological Products; D054812:Cyclitols; D003514:Cyclohexylamines; C000606097:kirkamide; D010165:Palladium
keywords: aminocyclitols; ecology; natural products; symbiosis; total synthesis