Dichloroketene-chiral olefin-based approach to pyrrolizidines: highly stereocontrolled synthesis of (+)-amphorogynine A.
[reaction: see text] A highly stereoselective route to (+)-amphorogynine A, a novel pyrrolizidine recently isolated from the New Caledonian plant Amphorogynine spicata, has been realized. The key step in the approach is a diastereoselective [2 + 2] dichloroketene-chiral enol ether cycloaddition (dr >or= 93:7) to access a dichlorocyclobutanone intermediate, which is converted into the alkaloid natural product via a pyrrolidinone derivative.
Roche
Caroline
C
Université Joseph Fourier de Grenoble, Chimie Recherche (LEDSS), 38041 Grenoble Cedex, France.
Delair
Philippe
P
Greene
Andrew E
AE
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003500:Cyclization; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009510:New Caledonia; D009993:Osmium Tetroxide; D010946:Plants, Medicinal / Q000737:chemistry; D011763:Pyrrolizidine Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D007202:Indicators and Reagents; D011763:Pyrrolizidine Alkaloids; C476522:amphorogynine A; D009993:Osmium Tetroxide