Phorboxazole synthetic studies. 2. Construction of a C(20-28) subtarget, a further extension of the Petasis-Ferrier rearrangement.
[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.
Smith
A B
AB
Department of Chemistry, University of Pennsylvania, Philadelphia 19104, USA. smithab@sas.upenn.edu
Minbiole
K P
KP
Verhoest
P R
PR
Beauchamp
T J
TJ
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
D006576:Heterocyclic Compounds, 4 or More Rings; D010080:Oxazoles; C408887:phorboxazole A