title: A concise approach to the core structures of pinnaic acid and halichlorine.
abstract: An efficient and flexible synthetic approach to the core structures of pinnaic acid and halichlorine is described using spirocyclic nitrone 4 as a key intermediate. 1,3-Dipolar cycloaddition of 4 with dipolarophile 8 provides access to the azaspirocyclic core of pinnaic acid 5 while the spiroquinolizidine core of halichlorine 6 has been synthesised via cycloaddition of 4 with dipolarophile 29. Nitrone 4 is accessed by oxidative ring opening of isoxazolidine 9. The utility of this synthetic strategy in the synthesis of C5 substituted analogues of pinnaic acid is also demonstrated.
authors: Department of Chemistry, The University of Auckland, 23 Symonds Street, Auckland, New Zealand.
authors: Sung-Hyun
authors: SH
authors: Yang
authors: G R
authors: GR
authors: Clark
authors: Vittorio
authors: V
authors: Caprio
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D009589:Nitrogen Oxides / Q000737:chemistry; D010084:Oxidation-Reduction; D010880:Piperidines / Q000737:chemistry; D011799:Quinazolines / Q000737:chemistry; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D009589:Nitrogen Oxides; D010880:Piperidines; D011799:Quinazolines; D013141:Spiro Compounds; C412666:halichlorine; C015388:nitrones; C412665:pinnaic acid; C032727:piperidine