A One- and Two-Dimensional 13C and 1H N.M.R. Study of Some Triterpenes of the Hopane, Stictane and Flavicene Groups

Abstract

The phase sensitive two-dimensional ( 2~) 1 3 c -'~ heteronuclear correlated and double quantum filtered cosy n.m.r. spectra of the triterpenes 7p-acetoxyhopan-22-01 and 2a,38,22atriacetoxystictane have been recorded at a resolution sufficient for the complete assignment of their proton resonances. Revisions to some of the methylene proton resonances of 78-acetoxyhopan-22-01 proposed elsewhere are discussed, and assignments for a series of flavicene and stictane triterpenes are presented. 21, n.m.r. analyses of a new triterpene isolated from the extracts of the lichen Pseudocyphellaria coronata revealed it to be 22a-hydroxystictano-25,3!34actone.

New Cytotoxic Lupane Triterpenoids from the Twigs of Coussarea paniculata

“…This assignment was supported by the key HMBC correlations shown in Figure and by the appearance of the C-3 oxymethine proton at δ 4.52 as a doublet of doublets. Further, the 13 C NMR values for carbons C-1 to C-5 of 2 were almost superimposable on those of 22α-hydroxystictano-25,3β-lactone, supporting the presence of a C-3/C-25 lactone in the A ring. The stereochemistry of the oxymethine proton at the C-3 position was assigned as α, like that of 22α-hydroxystictano-25,3β-lactone, on the basis of their almost identical coupling constants; this was supported by its NOESY correlation with the protons of the methyl group at the C-23 position resonating at δ 0.95.…”

Convenient Large-Scale Purification of Yessotoxin from Protoceratium reticulatum Culture and Isolation of a Novel Furanoyessotoxin

“…Stereochemistries of structurally significant skeletal portions (e.g., the side-chain structure of 2 ) were established in SELNOESY and NOESY experiments. Resolution in the 1 H axis in the g-HSQC spectra of 1 was such that stereochemistries of axially and equatorially oriented methylene protons attached to six-membered rings (but not seven- or eight-membered rings) could be distinguished , . Typically, axial methylene protons exhibited resolvable 2 J (geminal) and 3 J ax−ax couplings (ca.…”

Chemical Constituents from the Roots of Patrinia Rupestris

“…Optical rotations: Perkin-Elmer 341 Polarimeter; UV: Shimadzu UV-260 spectrophotometer; IR: Nicolet 170SX FT-IR instrument; EIMS: HP 5988A GC/MS instrument; HRESIMS: Bruker APEX II; 1 H NMR (400 MHz), 13 C NMR (100 MHz), NOEDS, 1 H-1 H COSY, HMQC, HMBC and NOESY: Varian Mercury-400BB NMR spectrometer; silica gel (200-300 mesh) for CC. and silica GF 254 for TLC was supplied by the Qingdao Marine Chemical factory.…”

“…H NMR (400 MHz),13 C NMR (100 MHz) and DEPT of compound 1 (CDCl 3 , TMS as internal standard, dTable 2. 1 H NMR (400 MHz), 13 C NMR (100 MHz) and DEPT of compound 2 (CDCl 3 , TMS as internal standard, d…”