Assignment of the absolute configuration of large molecules by ab initio calculation of the rotatory power within a small basis set scheme: the case of some biologically active natural products

2004 ◽  
Vol 15 (13) ◽  
pp. 1979-1986 ◽  
Author(s):  
Egidio Giorgio ◽  
Rosario G Viglione ◽  
Carlo Rosini
Keyword(s):  
Natural Products ◽  
Ab Initio ◽  
Absolute Configuration ◽  
Ab Initio Calculation ◽  
Rotatory Power ◽  
Biologically Active ◽  
Basis Set ◽  
Large Molecules ◽  
The Absolute ◽  
Active Natural

Determination of the Absolute Configuration of Bis(tetrahydropyran2-yl)methane by Comparison of Measured and Calculated CD-spectra

1998 ◽  
Vol 53 (8) ◽  
pp. 704-710 ◽  
Author(s):  
Jörg Fleischhauer ◽  
Christoph Jansen ◽  
Axel Koslowski ◽  
Gerhard Raabe ◽  
Jan Schiffer ◽  
...  
Keyword(s):  
Force Field ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Absolute Configuration ◽  
Vibrational Energy ◽  
Basis Set ◽  
Basis Sets ◽  
Am1 Method ◽  
Cd Spectra ◽  
The Absolute

Abstract The absolute configuration of bis(tetrahydropyran-2-yl)methane (1) was determined by comparison of measured and calculated CD spectra. The theoretical CD spectra were obtained by means of the CNDO/2S method. The five presumably lowest local minima on the energy hypersurface of the title compound were used to describe the conformer equilibrium mixture. The geometries of these conformers were calculated employing the MM3 force field, the semiempirical AM1 method and one-determinant ab initio calculations employing the 6-31G* basis set. Boltzmann factors were then obtained using relative energies calculated with three different basis sets and including correlation- and zero point vibrational energy. Based on the sign of the observed and calculated longest wavelength Cotton effect we assign an absolute configuration to the compound which is in keeping with the chirality expected from the assumed reaction mechanism. The results of force field and ab initio calculations converge to the point that the conformer equilibrium is dominated (85 -96%) by one single conformer which is energetically separated from the other conformers by about 2-3 kcal/mol. This result agrees with previous experimental data.

Biologically active natural products from Cassine viburnifolia

Planta Medica ◽  
2015 ◽  
Vol 81 (11) ◽  
Author(s):  
T Grkovic ◽  
R Akee ◽  
J Evans ◽  
JM Collins ◽  
B O'Keefe
Keyword(s):  
Natural Products ◽  
Biologically Active ◽  
Active Natural

Synthetic studies on biologically active natural products by a chemicoenzymatic approach

Tetrahedron ◽  
1984 ◽  
Vol 40 (1) ◽  
pp. 145-152 ◽  
Author(s):  
Masaji Ohno ◽  
Yukishige Ito ◽  
Masafumi Arita ◽  
Tomoyuki Shibata ◽  
Kunitomo Adachi ◽  
...  
Keyword(s):  
Natural Products ◽  
Biologically Active ◽  
Synthetic Studies ◽  
Active Natural

Back to the Roots: Prediction of Biologically Active Natural Products from Ayurveda Traditional Medicine

2011 ◽  
Vol 30 (2-3) ◽  
pp. 181-187 ◽  
Author(s):  
Honey Polur ◽  
Tejal Joshi ◽  
Christopher T. Workman ◽  
Gandhidas Lavekar ◽  
Irene Kouskoumvekaki
Keyword(s):  
Natural Products ◽  
Traditional Medicine ◽  
Biologically Active ◽  
Active Natural
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