title: Development of a flexible approach to Nuphar alkaloids via two enantiospecific piperidine-forming reactions.
abstract: In this paper we describe the stereoselective synthesis of functionalized lactam 7 via two enantiospecific piperidine-forming techniques and its employment in a general synthetic approach to Nuphar alkaloids. Specifically, the formation of piperidine 18 by formal [3 + 3] cycloaddition and stepwise annelation processes is described; the latter technique was found to be significantly more efficient than the Pd-catalyzed TMM addition process. Finally, exploitation of the exocyclic alkene installed in the piperidine-forming reaction in the transformation of 18 to (-)-deoxynupharidine ((-)-2), (-)-castoramine ((-)-3), and (-)-nupharolutine ((-)-4) via intermediate lactam 7 is delineated.
authors.affiliation: Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
authors.forename: Katharine M
authors.initials: KM
authors.lastname: Goodenough
authors.forename: Wesley J
authors.initials: WJ
authors.lastname: Moran
authors.forename: Piotr
authors.initials: P
authors.lastname: Raubo
authors.forename: Joseph P A
authors.initials: JP
authors.lastname: Harrity
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis*; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D007769:Lactams / Q000737:chemistry; D015394:Molecular Structure; D031654:Nuphar / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry; D010880:Piperidines / Q000138:chemical synthesis / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry; D011807:Quinolizines / Q000138:chemical synthesis*; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D007769:Lactams; D010880:Piperidines; D011807:Quinolizines; C010908:deoxynupharidine; D010165:Palladium; C032727:piperidine