Chiroptical properties of pyrrolidine derivatives

1983 ◽  
Vol 48 (6) ◽  
pp. 1618-1623
Author(s):  
Otakar Červinka ◽  
Ilja Sedlák ◽  
František Strejček
Keyword(s):  
Wave Function ◽  
Absolute Configuration ◽  
Molecular Geometry ◽  
Cd Spectra ◽  
Chiroptical Properties ◽  
Total Gradient ◽  
Gradient Optimization ◽  
Chemical Correlation ◽  
Rotational Strengths

CD spectra of (S)-(-)-2-phenyl-1-methylpyrrolidine (I) and (S)-(-)-1-methyl-2-(2-tolyl)pyrrolidine (II) were calculated. Rotational strengths were calculated by direct procedure based on the CNDO/S-CI wave function. The most stable conformations were determined by total gradient optimization of molecular geometry and their molar fractions were calculated. CD spectra, constructed from the molar fractions and rotational strengths, agreed well with the experimental ones. Absolute configuration of compound II was established by the chemical correlation with (S)-(-)-hygrinic acid.

CD-Spectroscopic Investigations for the Determination of the Absolute Configuration of α-Alkylated 1,4-CycIohexanedione Derivatives

2000 ◽  
Vol 55 (11) ◽  
pp. 1011-1014 ◽  
Author(s):  
Jörg Fleischhauer ◽  
Sven Gabriel ◽  
Dieter Ender ◽  
Anja Nühring ◽  
Axel Wollmer
Keyword(s):  
Absolute Configuration ◽  
Membered Ring ◽  
Cd Spectra ◽  
Pure Material ◽  
Enantiomerically Pure ◽  
System 2 ◽  
The Absolute ◽  
Stereogenic Center ◽  
Rotational Strengths

The absolute configuration of the conformationally flexible six membered ring system 2-methyl- and 2,6-dimethyl-l,4-cyclohexanedione monoethylene acetal was determined by comparison of measured and calculated CD spectra. The rotational strengths were calculated by means of the CNDO/S-method assuming R at the stereogenic center. The results were compared with the predictions made by the octant rule. The enantiomerically pure material was synthesized via the corresponding SAMP- and RAMP-hydrazones.

Study of chiroptical properties of some piperidine derivatives

1983 ◽  
Vol 48 (6) ◽  
pp. 1624-1634
Author(s):  
Otakar Červinka ◽  
Anna Fábryová ◽  
Vladimír Šňupárek ◽  
František Strejček
Keyword(s):  
Wave Function ◽  
Chiroptical Properties ◽  
Cd Spectrum ◽  
Chemical Correlation ◽  
The Individual ◽  
Theory And Experiment

Chiroptical properties of (S)-(-)-1-methyl-2-phenylpiperidine and (S)-(-)-1-methyl-2-(2-tolyl)piperidine have been studied. The preferred conformations have been calculated in gradient way on the basis of the CNDO/2 method, and the rotational forces have been calculated for them by direct procedure using the CNDO/S-CI wave function. For comparison of theory and experiment, molar fractions of the individual conformers have been calculated and used together with the rotational forces for construction of the CD spectrum which has been compared with the experimental CD spectrum. Absolute configurations of the mentioned compounds have been determined by chemical correlation.

Absolute configuration at C(20) of the derivatives of 21-nor-5α-cholane-20,24-diol

1980 ◽  
Vol 45 (9) ◽  
pp. 2443-2451
Author(s):  
Vladimír Pouzar ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Side Chain ◽  
Chemical Correlation ◽  
The Absolute ◽  
Derivatives Of

Derivatives of 21-nor-5α-cholane-20,24-diol XI and XIX were prepared by stepwise construction of the side-chain in the position 17β. Their absolute configuration at C(20) was determined on the basis of chemical correlation with the derivatives of 21-nor-5α-cholan-20-ol, XVI and XXIV. The absolute configuration of alcohols XVI and XXIV was determined from the ratio of the yields in which they are formed during the reduction of ketone X and using the benzoate rule. To compounds XI-XVIII the configuration 20R and to compounds XIX-XXVI the configuration 20S has been assigned.

Preparation and absolute configuration at C(20) of 21-nor-5α-chol-22-en-24→20-olide derivatives

1981 ◽  
Vol 46 (4) ◽  
pp. 917-925 ◽  
Author(s):  
Vladimír Pouzar ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Nmr Spectra ◽  
Lithium Salt ◽  
H Nmr ◽  
Chemical Correlation ◽  
Unsaturated Lactones

Reaction of the aldehyde I with the lithium salt of 1-(2-tetrahydropyranyloxy)-2-propyne yielded the compounds II and IV. From the compound II the lactone XII was prepared via the intermediates III and X, the lactone XVIII was prepared from the substance IV via the intermediates V and XVI. The unsaturated lactones XII and XVIII were also prepared by sulfenylation and dehydrosulfenylation of the saturated lactones XIII and XIX. Based on chemical correlation and 1H-NMR spectra analyses of the compounds II and IV, the lactone XII was assigned the 20R-configuration whereas the lactone XVIII was allotted the 20S-configuration.

Preparation and absolute configuration at C(22) of 21,26,27-trinor-5α-cholestane-22,25-diol derivatives

1983 ◽  
Vol 48 (8) ◽  
pp. 2423-2435 ◽  
Author(s):  
Vladimír Pouzar ◽  
Soňa Vašíčková ◽  
Pavel Drašar ◽  
Ivan Černý ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Lithium Salt ◽  
Nickel Acetylacetonate ◽  
Cotton Effects ◽  
Chemical Correlation

Reaction of 5α-pregnan-21-al (V), obtained from ester of the corresponding acid III via the alcohol IV, with lithium salt of 1-methoxymethoxy-2-propyne afforded both the isomeric 25-methoxymethoxy-21,26,27-trinor-5α-cholest-23-yn-22-ols (VI and VIII) which were converted into two 21,26,27-trinor-5α-cholestane-22,25-diols (XI, XV). Absolute configuration of the alcohols X and XIV was assigned by chemical correlation with derivatives XXVI and XXVII of known absolute configuration at C(20). The correlation was based on reduction of thiocarbonates derived from the diols XXII and XXIV for which also Cotton effects of their complexes with nickel acetylacetonate were studied. Both diols were prepared from 5α-pregnan-20-one (XVIII) via 5α-pregn-20-yne (XIX) and the 21,26,27-trinor-5α-cholest-20-ene derivative XXI.

scholarly journals Messung und Berechnung der CD-Spektren der Biaryl-Alkaloide Ancistrocladein und Dioncophyllein A [1] / Detection and Calculation of the CD Spectra from the Biaryl Alkaloids Ancistrocladeine and Dioncophylleine A [1]

1993 ◽  
Vol 48 (2) ◽  
pp. 140-148 ◽  
Author(s):  
J. Fleischhauer ◽  
A. Koslowski ◽  
B. Kramer ◽  
E. Zobel ◽  
G. Bringmann ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Cd Spectra ◽  
Circular Dichroïsm

AbstractThe circular dichroism (CD) of the biaryls ancistrocladeine and dioncophylleine A has been studied. The CNDO/S method in combination with a Boltzmann weighting o f different structures using AM 1 energies has been applied to reproduce the experimental CD spectra o f the two alkaloids with known absolute configuration at with those o f the exciton chirality method.

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