Two stereoisomeric pentacyclic oxindole alkaloids from Uncaria tomentosa: uncarine C and uncarine E.
The chloroform solvate of uncarine C (pteropodine), (1'S,3R,4'aS,5'aS,10'aS)-1,2,5',5'a,7',8',10',10'a-octahydro-1'-methyl-2-oxospiro[3H-indole-3,6'(4'aH)-[1H]pyrano[3,4-f]indolizine]-4'-carboxylic acid methyl ester, C(21)H(24)N(2)O(4).CHCl(3), has an absolute configuration with the spiro C atom in the R configuration. Its epimer at the spiro C atom, uncarine E (isopteropodine), (1'S,3S,4'aS,5'aS,10'aS)-1,2,5',5'a,7',8',10',10'a-octahydro-1'-methyl-2-oxospiro[3H-indole-3,6'(4'aH)-[1H]pyrano[3,4-f]indolizine]-4'-carboxylic acid methyl ester, C(21)H(24)N(2)O(4), has Z' = 3, with no solvent. Both form intermolecular hydrogen bonds involving only the oxindole, with N.O distances in the range 2.759 (4)-2.894 (5) A.
Muhammad
I
I
National Center for Natural Products Research, RIPS, School of Pharmacy, University of Mississippi, University, MS 38677, USA.
Khan
I A
IA
Fischer
N H
NH
Fronczek
F R
FR
D000470:Alkaloids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007211:Indoles / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D000078183:Oxindoles; D010946:Plants, Medicinal / Q000737:chemistry*; D013141:Spiro Compounds / Q000737:chemistry*; D013237:Stereoisomerism
D000470:Alkaloids; D007211:Indoles; D000078183:Oxindoles; D013141:Spiro Compounds; C431786:uncarine E; C431785:uncarine C