Furanophane transannular Diels-Alder approach to (+)-chatancin: an asymmetric total synthesis of (+)-anhydrochatancin.
(+)-anhydrochatancin was synthesized while attempting an enantioselective total synthesis of (+)-chatancin. The presented route constitutes the furanophane approach, one of the two ways of proposed biosynthesis which may involve transannular Diels-Alder (TADA) reaction to link this diterpene biogenetically to the furanocembranoids. Highlights of the synthetic work include the assembly of chiral, acyclic, trisubstituted furan 28 via a coupling of aldehyde 10 and dilithiofuroic acid 11, a macrocyclization to furanophane 29E via ring-closing metathesis, a TADA reaction to reach tetracyclic intermediate 4, and a hydride shift mediated oxygen transposition as a final rearrangement to the target. Unfortunately, the strongly acidic condition required for the last step allows only the isolation of anhydrochatancin 30 due to the acid sensitivity of chatancin 1.
Toró
András
A
Laboratoire de Synthèse Organique, Institut de Pharmacologie, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada.
Deslongchamps
Pierre
P
D000447:Aldehydes / Q000138:chemical synthesis; D037421:Anthozoa / Q000737:chemistry*; D003500:Cyclization; D004224:Diterpenes / Q000138:chemical synthesis*; D005663:Furans / Q000737:chemistry*; D007202:Indicators and Reagents; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D013237:Stereoisomerism
D000447:Aldehydes; D004224:Diterpenes; D005663:Furans; D007202:Indicators and Reagents; C414662:chatancin; C481819:furanophane