Biomimetic synthesis of xuxuarines Ealpha and Ebeta: structure revision of Rzedowskia bistriterpenoids.
Reaction of pristimerin with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) resulted in a biomimetic-type coupling leading to xuxuarines Ealpha and Ebeta and not the previously reported Rzedowskia bistriterpenoids I and II suggesting that the structures proposed for these natural products need revision. A product obtained in this reaction by an unusual Diels-Alder addition followed by retro-Diels-Alder-type elimination was characterized as pristimerin dicyanophenalenedione. Complete 1H, and 13C NMR spectral assignments of xuxuarines Ealpha and Ebeta have been made by the application of 1D and 2D NMR techniques.
Jacobsen
Neil E
NE
Department of Chemistry, College of Arts and Sciences, The University of Arizona, Tucson, AZ 85721, USA.
Wijeratne
E M Kithsiri
EM
Corsino
Joaquim
J
Furlan
Maysa
M
Bolzani
Vanderlan da S
Vda S
Gunatilaka
A A Leslie
AA
D016227:Benzoquinones / Q000737:chemistry; D001688:Biological Products / Q000737:chemistry; D032701:Biomimetics / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D053978:Pentacyclic Triterpenes; D013729:Terpenes / Q000138:chemical synthesis* / Q000737:chemistry; D014315:Triterpenes / Q000737:chemistry*
D016227:Benzoquinones; D001688:Biological Products; D053978:Pentacyclic Triterpenes; D013729:Terpenes; D014315:Triterpenes; C529245:xuxuarine E*; C529246:xuxuarine Ebeta; C050414:celastrol