¹³C chemical shifts of some model olefins

Abstract

Abstract-An extensive carbon-1 3 nuclear magnetic resonance study of selected model olefins dissolved in deuteriochloroform has been carried out under standardized conditions. Assignments of the chemical shifts have been made. The influence of the nature of the solvent and the effect of changing the concentration of the solute have been investigated. The results are intended to provide a practical aid for the analysis of olefinic materials.

A new ceramide from Ramaria botrytis (Pers.) Ricken

“…The geometry of the double bond at C-4 was deduced to be E from the 1 H-1 H coupling constant (J = 15.4 Hz) between H-4 and H-5. The chemical shift value of the olefinic methyl group at C-9 (d C 16.0) suggests that the double bond at C-8 is E geometry [10]. The same conclusion was derived from the nuclear Overhauser enhancement spectroscopy (NO-ESY) cross peak observed between H-8 and H 2 -10.…”

Ceramide Constituents from Five Mushrooms.

“…The Et 2 O extract (3.7 g) was chromatographed on a silica gel column using hexane-EtOAc (7 : 3-1 : 7), EtOAc and MeOH, to afford 20 fractions (frs. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Fraction 17 was purified by preparative HPLC to give 3 (1.9 mg) and 4 (1.8 mg).…”

Complete 1H and 13C NMR assignment for aryl diisoprenes

“…The E-configuration of the double bond was verified by the position of the C-16 methyl carbon signal observed around 16 ppm and one methylene unit (C-5) around 39 ppm in the 13 C NMR spectra for 1-4 (Table 2). 10 The 1 H NMR spectra showed the benzylic methylene groups (H-9) at 2.76 (1), 2.59 (2), 2.68 (3) and 2.59 (4) ppm. DEPT experiments indicated one more methylene signal (¾26 ppm), which was unambiguously assigned to H-4.…”