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Search for "Karplus equation" in Full Text gives 6 result(s) in Beilstein Journal of Organic Chemistry.
Syn-selective silicon Mukaiyama-type aldol reactions of (pentafluoro-λ6-sulfanyl)acetic acid esters with aldehydes
Beilstein J. Org. Chem. 2018, 14, 373–380, doi:10.3762/bjoc.14.25
- constants of 2.4–4.0 Hz. The products 3 produced as minor compounds in the present study had coupling constants between 3.3 and 4.0 Hz, which is typical for a gauche arrangement of the coupling nuclei according to the Karplus equation. Also the other NMR data agree with those found for authentic anti-aldol
Remarkable functions of sn-3 hydroxy and phosphocholine groups in 1,2-diacyl-sn-glycerolipids to induce clockwise (+)-helicity around the 1,2-diacyl moiety: Evidence from conformation analysis by 1H NMR spectroscopy
Beilstein J. Org. Chem. 2017, 13, 1999–2009, doi:10.3762/bjoc.13.196
- ; deuterium labeling; sn-glycerol; glycerolipids; glycerophospholipids; helicity; Karplus equation; proton NMR spectroscopy; staggered conformers; Introduction Glycerophospholipids, constituting the basic elements of cytoplasm bilayer membranes, are responsible for several cell functions [1][2][3]. These
- limit (100%). This result is in good agreement with the conformational properties of cell-membrane glycerophospholipids reported previously [10][11][12][13][14][15]. On the other hand, in our calculations using Equation 2 as the advanced Karplus equation [18], the helical volumes of these
- relations established in our preceding 1H NMR and CD studies. Calculation of fractional populations (%) of three staggered conformers around the 1,2-diacyl group with a Karplus relation A general Karplus equation of Haasnoot et al. [40] is extended into the simultaneous linear equations Equation 1 [22] and
Synthesis of the C8’-epimeric thymine pyranosyl amino acid core of amipurimycin
Beilstein J. Org. Chem. 2016, 12, 1765–1771, doi:10.3762/bjoc.12.165
- between the H5’ and H4’a/H4’e as ≈150°/25°. This justifies the observed coupling constants in the 1H NMR between H5’ and H4’ (JH4’a, H5’a = 8.3 Hz and JH4’e, H5’a = 7.4 Hz) based on the Karplus equation [21]. This observation also confirms the assigned configurations as 5’R and 6’S in 13. The experimental
Strecker degradation of amino acids promoted by a camphor-derived sulfonamide
Beilstein J. Org. Chem. 2016, 12, 732–744, doi:10.3762/bjoc.12.73
- for atom numbering). The proton H4B appears as doublet due to the coupling with H5B(exo) while the corresponding coupling constant to H5B(endo) is predicted from the Karplus equation to be low (0.2 Hz) according to the calculated dihedral angle H4B–C4B–C5B–H5B(endo) of 76.1°, and is thus not resolved
- , for the (S)-3A and the (R)-3A isomer. According to the Karplus equation, these values correspond to coupling constants of 5.0–5.5 Hz and 1.5–2.0 Hz, respectively, thus corroborating the (S)-3A configurational assignment. Mechanism Having identified and structurally characterized compound 2 it remained
Aluminacyclopentanes in the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes
Beilstein J. Org. Chem. 2016, 12, 406–412, doi:10.3762/bjoc.12.43
- than JPC2 = 3.0 Hz in compound 13b. In view of the fact that the phosphorus–carbon constants obey the Karplus equation [22], this result suggests that the conformation of the five-membered heterocycle changes upon the formation of the complex with molybdenum hexacarbonyl. Similarly, bisphospholanes 10a
Dioxane dibromide mediated bromination of substituted coumarins under solvent-free conditions
Beilstein J. Org. Chem. 2012, 8, 323–329, doi:10.3762/bjoc.8.35
- -lactone moiety (Table 1, entry 1). This was evident from the dihedral angle between H–C3–C4 and C3–C4–H in 2a, which was calculated (from the Karplus equation) as 57.5° from the coupling constant (2.6 Hz) between C3–H and C4–H at δ 4.96 and δ 5.34. However, for the aromatic ring substituted with the
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