Zur absoluten Konfiguration von Cassain

Abstract

Volumen 48, Fasciculus 5 (1965) -No. 119 LITERATURVERZEICHNI S I ) Auszug itus der Diss. E. ISELI, Hasel 1963. 2, 30. Mitt. vgl. E. ISELI ct al. [l].

Alkaloidal Constituents ofCrinum bulbispermumIII: Bulbispermine, a New Alkaloid ofCrinum bulbispermum1

“…Plant material and cell culture conditions Cells of Catharanthus roseus (L.) 0. Don derived from a single seedling (4) were routinely transferred every eight days into 100 ml of fresh medium according to (10)…”

<b>ANTIMICROBIAL DITERPENOID ALKALOIDS FROM <i>ERYTHROPHLEUM SUAVEOLENS</i> (GUILL. & PERR.) BRENAN</b>

“…HMBC correlations from H-5 (Scheme 1) to the carbons at δ C 209.6 (C-6), 36.2 (C-4), 74.8 (C-7), 44.0 (C-9) and 76.4 (C-3) confirmed the substitution pattern of ring B. The expected E configuration of the 13,18 double bond [5,[7][8][9] is evident from the deshielding effect of the side chain carbonyl function (δ C 168.8) of one of the two allylic protons (δ H 2.09 and 2.76) at C-12 (δ C 23.3). The two methylene proton signals at δ H 3.50 (t, J = 6 Hz) and 3.70 (t, J = 6 Hz) were clearly visible on the 1 H-1 H COSY spectrum as an isolated correlation system It is noteworthy that the signals of H-18, N-methyl, N-methylene and O-methylene groups were doubled, as expected, in both the 1 H and 13 C NMR spectra of 1 and 2 as a result of restricted rotation about the amide bond [10].…”

Facile Approach to Versatile Chiral Intermediates for Fused Cyclopentanoid Natural Products

“…The compounds 5a, 5c, and 5d showed similar chemical shifts and coupling constants, revealing equatorial disposi tion of the ester moiety. A n equatorial disposition of the ester moiety was expected to lead to £-alkylidene isomers [7] which was authenticated by N O E difference measurements. In each case, strong N O E interactions were observed between olefinic protons and the m ethylene protons of the ethoxy groups, thereby revealing their spatial proximity.…”