title: Asymmetric synthesis of all the known phlegmarine alkaloids.
abstract: The asymmetric synthesis of all four of the known natural phlegmarines and one synthetic derivative has been accomplished in 19-22 steps from 4-methoxy-3-(triisopropylsilyl)pyridine. Chiral N-acylpyridinium salt chemistry was used twice to set the stereocenters at the C-9 and C-2' positions of the phlegmarine skeleton. Key reactions include the use of a mixed Grignard reagent for the second N-acylpyridinium salt addition, zinc/acetic acid reduction of a complex dihydropyridone, and a von Braun cyanogen bromide N-demethylation of a late intermediate. These syntheses confirmed the absolute stereochemistry of all of the known phlegmarines.
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States.
authors.forename: Bradley H
authors.initials: BH
authors.lastname: Wolfe
authors.forename: Adam H
authors.initials: AH
authors.lastname: Libby
authors.forename: Rima S
authors.initials: RS
authors.lastname: Al-Awar
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Foti
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Comins
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D007202:Indicators and Reagents / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D007202:Indicators and Reagents