title: Phorboxazole synthetic studies. 2. Construction of a C(20-28) subtarget, a further extension of the Petasis-Ferrier rearrangement.
abstract: [formula: see text] In this, the second of two Letters, we describe the efficient assembly of (+)-4, a C(20-28) subtarget for the total synthesis of phorboxazoles A (1) and B (2). The synthesis was achieved in 12 linear steps (20% overall yield) via Petasis-Ferrier rearrangement of an E/Z mixture of trisubstituted enol ethers (15) to assemble the C(22-26) cis-tetrahydropyran. A mechanism for the observed diastereoconvergence of 15 is proposed. In addition, a new tactic for the synthesis of enol ethers (e.g., 15) based on the elegant work of Julia is described.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia 19104, USA. smithab@sas.upenn.edu
authors.forename: A B
authors.initials: AB
authors.lastname: Smith
authors.forename: K P
authors.initials: KP
authors.lastname: Minbiole
authors.forename: P R
authors.initials: PR
authors.lastname: Verhoest
authors.forename: T J
authors.initials: TJ
authors.lastname: Beauchamp
mesh_terms: D006576:Heterocyclic Compounds, 4 or More Rings / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D010080:Oxazoles / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction
chemical_list: D006576:Heterocyclic Compounds, 4 or More Rings; D010080:Oxazoles; C408887:phorboxazole A