On the structure of palau'amine: evidence for the revised relative configuration from chemical synthesis.
Hexacyclic congeners 3 and 4 of palau'amine, which incorporate both guanidine functional groups and have the cis configuration of the azabicyclo[3.3.0]octane core, are prepared in 14 steps from cycloadduct 6. Synthetic access to these analogues allows the first direct comparison of NMR data for hexacyclic diguanidine structures having the originally proposed cis-azabicyclo[3.3.0]octane fragment with data for natural alkaloids of the palau'amine family. This comparison provides convincing evidence in favor of the recently proposed structural revision of these marine alkaloids, fully supporting the trans configuration of the central azabicyclo[3.3.0]octane ring system of palau'amine and congeners.
Lanman
Brian A
BA
Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, CA 92697-2025, USA.
Overman
Larry E
LE
Paulini
Ralph
R
White
Nicole S
NS
D002244:Carbon / Q000737:chemistry; D002625:Chemistry, Organic / Q000379:methods*; D019281:Dimerization; D019791:Guanidine / Q000737:chemistry; D006146:Guanidines / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008968:Molecular Conformation; D015394:Molecular Structure; D009795:Octanes / Q000737:chemistry; D011758:Pyrroles / Q000737:chemistry; D013141:Spiro Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature
D006146:Guanidines; D009795:Octanes; D011758:Pyrroles; D013141:Spiro Compounds; C438976:palau'amine; D002244:Carbon; D019791:Guanidine; C026728:octane