Alkaloids of Stephania glabra. Direct chemical correlation of the absolute configuration of some benzyltetrahydroisoquinoline, proaporphine, and aporphine alkaloids. New protoberberine alkaloid

1968 ◽  
Vol 33 (7) ◽  
pp. 2785-2789 ◽  
Author(s):  
M. P. Cava ◽  
K. Nomura ◽  
S. K. Talapatra ◽  
M. J. Mitchell ◽  
R. H. Schlessinger ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Chemical Correlation ◽  
The Absolute ◽  
Protoberberine Alkaloid

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.

Structure of isosilerolide, relative and absolute configuration of silerolide and lasolide - Sesquiterpenic lactones of new stereoisomeric type of eudesmanolides

1986 ◽  
Vol 51 (4) ◽  
pp. 903-929 ◽  
Author(s):  
Miroslav Holub ◽  
Miloš Buděšínský ◽  
Zdenka Smítalová ◽  
David Šaman ◽  
Urszula Rychłewska
Keyword(s):  
Absolute Configuration ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Nmr Data ◽  
Chemical Correlation ◽  
The Absolute

On the basis of spectroscopic, particularly 1H NMR data, isosilerolide was assigned structure I, including the absolute configuration. The structure was confirmed by X-ray diffraction. Isosilerolide represents a new stereoisomeric type of natural eudesmanolides, characterized as 5βH, 6αH, 7αH, 10αCH3-eudesman-6,12-olide. As shown by the chemical correlation of isosilerolide (I) with silerolide (III) and lasolide (X), the latter two natural lactones belong to this stereoisomeric group of eudesmanolides. Analysis of models and 1H NMR data shows that structures of some eudesman-6,12-olides, published by other authors, should be corrected.

Enantioselective Diels-Alder reaction of (E)-1-trimethylsilyloxy-1,3-butadiene with chiral glyoxylates

1990 ◽  
Vol 55 (1) ◽  
pp. 230-244 ◽  
Author(s):  
Otakar Červinka ◽  
Aleš Svatoš ◽  
Petr Trška ◽  
Pavel Pech
Keyword(s):  
Nmr Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Absolute Configuration ◽  
Quantum Chemical ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Chemical Correlation ◽  
The Absolute ◽  
C Nmr

Enantioselective Diels-Alder reaction of (E)-1-trimethylsilyloxy-1,3-butadiene (I) with chiral (-)-menthyl (II) and (-)-8-phenylmenthyl (III) glyoxylates in various solvents without or with catalysts was studied. The reactions gave a mixture of trans-and cis-isomers of (-)-menthyl (IV) and (-)-8-phenylmenthyl (V) 2-trimethylsilyloxy-5,6-dihydro-2H-pyran-6-carboxylates. The regioselectivity of the reaction was explained by quantum-chemical calculations, the enantioselectivity was determined using 13C NMR spectroscopy and the absolute configuration of the addition products was assigned on the basis of chemical correlation with (S)-(-)-dimethyl malate.

scholarly journals Determination of the absolute configuration of 6 -Hydroxitricyclo[ 6.2.1.02,7]undeca-9-ene-3-one by chemical correlation

2013 ◽  
Author(s):  
Felícia Megumi Ito ◽  
Suély Copini ◽  
Nathália Rodrigues de Almeida ◽  
Kelly Karoliny Lima Pedroni ◽  
Ana Camila Micheletti ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Chemical Correlation ◽  
The Absolute

scholarly journals The Absolute Configuration of Cularine : A Chemical Correlation to L (S)-Laudanosine

1971 ◽  
Vol 19 (10) ◽  
pp. 2197-2199 ◽  
Author(s):  
JUNICHI KUNITOMO ◽  
KEIKO MORIMOTO ◽  
KEIKO YAMAMOTO ◽  
YOHKO YOSHIKAWA ◽  
KEIKO AZUMA ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Chemical Correlation ◽  
The Absolute
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