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.

scholarly journals The symmetrical spiro -heptanediamine and its resolution into optically active components

1936 ◽  
Vol 154 (881) ◽  
pp. 53-60 ◽  
Keyword(s):  
Carbon Atom ◽  
Optical Activity ◽  
Optically Active ◽  
Active Components ◽  
Asymmetric Carbon Atom ◽  
Molecular Configuration ◽  
Experimental Realization ◽  
Asymmetric Carbon ◽  
Acetic Acids

The experimental realization of the simplest possible types of molecular configuration which can show optical activity in the amorphous con­dition is important in connexion with stereochemical theory. Among optically active spiranes containing no asymmetric carbon atom such simple types are found in the d - and l -1-methyl- cyclo -hexylidene-4-acetic acids and the d - and 1-spiro- 5:5-dihydantoins, but no satisfactory case has hitherto been described of optical activity in substances of the constitution H —C—( CH 2 ) n —C—(CH 2 ) n —X X —C—( CH 2 ) n —C—(CH 2 ) n —H. One of the simplest conceivable examples of the latter kind should be found in the previously unknown symmetrical spiro -heptanediamine of the constitution— NH 2 —C—CH 2 —C—CH 2 —C—H H—C—CH 2 —C—CH 2 —C—NH 2 .

Reaction of 3-phenyl-1,2,4-triazin-5(4H)-one under acylating conditions with natural alcohols containing an asymmetric carbon atom

2012 ◽  
Vol 48 (4) ◽  
pp. 625-633 ◽  
Author(s):  
I. N. Egorov ◽  
G. V. Zyryanov ◽  
P. A. Slepukhin ◽  
T. A. Tseitler ◽  
V. L. Rusinov ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Asymmetric Carbon Atom ◽  
Asymmetric Carbon

Cobalt(III) Complexes of a Stereospecific Ligand Derived from (S)-Proline

1979 ◽  
Vol 32 (8) ◽  
pp. 1661 ◽  
Author(s):  
T Woon ◽  
MJ O'Conner
Keyword(s):  
Aqueous Solution ◽  
Carboxylic Acid ◽  
Absolute Configuration ◽  
Cotton Effect ◽  
Low Energy ◽  
Spectral Measurements ◽  
Asymmetric Carbon Atom ◽  
Geometrical Isomers ◽  
Negative Cotton Effect ◽  
Asymmetric Carbon

The quadridentate ligand, (2S,2'S)-1,1'-(ethane-1,2-diyl)bis(pyrrolidine-2-carboxylic acid) dihydrochloride (H2pren,2HCl), has been derived from (S)-proline. The preparations of the cobalt(III) complexes Na [Co(pren)(CO3)],3H2O, [CO(pren)(H2O)2] ClO4,- 2H2O and [Co(pren)(H2O)Cl],1�5H2O are described. All exist as cis-α geometrical isomers. 13C N.M.R. and absorption spectral measurements confirm the cis-α arrangement. The complex cis-α- [Co(pren)(H2O)Cl],1�5H2O rapidly aquates with retention of configuration. The compounds having actual or near C2 symmetry exhibit a strong negative c.d. band under the 1A1g → 1T1g cubic absorption band which is due to the 1A1 →1E tetragonal component, consistent with the Δ absolute configuration imposed by the (S) configuration of the asymmetric carbon atom in the (S)-proline moiety. The o.r.d. spectrum of cis-α-Na [Co(pren)CO3],3H2O in aqueous solution has a negative Cotton effect at low energy as expected for the Δ absolute configuration.

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