Asymmetric transformation as a means for determination of absolute configuration of acid with an asymmetric carbon atom in the α-position

1966 ◽  
Vol 0 (20) ◽  
pp. 761-762
Author(s):  
O. Červinka ◽  
L. Hub
Keyword(s):  
Carbon Atom ◽  
Absolute Configuration ◽  
Asymmetric Carbon Atom ◽  
Determination Of Absolute Configuration ◽  
Asymmetric Transformation ◽  
Asymmetric Carbon

The Decomposition of Lasiocarpic and Echimidinic Acids in Hydrochloric Acid

1960 ◽  
Vol 13 (2) ◽  
pp. 269 ◽  
Author(s):  
HC Crowley ◽  
CCJ Culvenor
Keyword(s):  
Carbon Atom ◽  
Hydrochloric Acid ◽  
Absolute Configuration ◽  
Dilute Hydrochloric Acid ◽  
Methoxyl Group ◽  
Asymmetric Carbon Atom ◽  
Asymmetric Carbon

In concentrated hydrochloric acid at 100 �C, lasiocarpic acid is readily decomposed with formation principally of acetaldehyde, dimethylpyruvic acid, and α-keto-ββ-dimethyl-γ-valerolactone. Echimidinic acid is similarly and more rapidly decomposed while trachelanthic and heliotric acids are stable at 100 �C. In dilute hydrochloric acid, lasiocarpic acid is slowly converted into acetaldehyde, acetone, dimethylpyruvic acid, (+)-2-methoxy-4-methylpentan-3-one (IX), 2-methylpent-1-en-3-one (XI), and an unidentified compound. The isolation of IX shows that lasiocarpic and heliotric acids have the same absolute, configuration at the asymmetric carbon atom which bears the methoxyl group.

Studies on the biosynthesis of cholesterol XVIII. The stereospecificity of mevaldate reductase and the biosynthesis of asymmetrically labelled farnesyl pyrophosphate

1966 ◽  
Vol 163 (993) ◽  
pp. 465-491 ◽  
Keyword(s):  
Carbon Atom ◽  
Absolute Configuration ◽  
Farnesyl Pyrophosphate ◽  
Asymmetric Carbon Atom ◽  
Isotopic Label ◽  
Asymmetric Carbon

It is demonstrated that mevaldate reductase transfers hydrogen stereospecifically from the ‘Aʼ-side of NADH or NADPH to substrate. When 4 R -[ 3 H 1 ]NADH, or NADPH, is used for the reduction of mevaldate the resulting [5. 3 H 1 ]mevalonate is stereospecifically labelled at C-5 with an absolute configuration of R . Mevaldate reductase shows no stereospecificity for the asymmetric carbon atom, C-3, in mevaldate: the product of the reduction of 3 RS -mevaldate is 3 RS -mevalonate. 5 R -[5. 3 H 1 ]- and 5 R -[5-D 1 ]mevalonate have been prepared and used for the synthesis of 1 R -[1,5,9. 3 H 3 ]- and 1 R -[1,5,9-D 3 ]farnesyl pyrophosphate and squalene. It is shown that when squalene is synthesized from such farnesyl pyrophosphate all the isotopic label appears in the squalene without loss. The implications of the last observations are discussed in the light of previous results.

Prismatomerin, a New Iridoid fromPrismatomeristetrandra. Structure Elucidation, Determination of Absolute Configuration, and Cytotoxicity

2007 ◽  
Vol 70 (8) ◽  
pp. 1339-1343 ◽  
Author(s):  
Karsten Krohn ◽  
Dietmar Gehle ◽  
Sujit Kumar Dey ◽  
Nilufar Nahar ◽  
Mohammed Mosihuzzaman ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Structure Elucidation ◽  
Determination Of Absolute Configuration
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