scholarly journals Studies on Optically Active Amino Acids. XI. Studies on α-Alkyl-α-amino Acids. VI. Chemical Correlation of Absolute configuration of α-Methylphenylalanine to α-Methylaspartic Acid

1966 ◽  
Vol 14 (10) ◽  
pp. 1138-1143 ◽  
Author(s):  
Shiro Terashima ◽  
Kazuo Achiwa ◽  
Shun-ichi Yamada
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Optically Active ◽  
Methylaspartic Acid ◽  
Chemical Correlation

scholarly journals Asymmetric Synthesis of Tetrasubstituted α-Aminophosphonic Acid Derivatives

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3202
Author(s):  
Aitor Maestro ◽  
Xabier del Corte ◽  
Adrián López-Francés ◽  
Edorta Martínez de Marigorta ◽  
Francisco Palacios ◽  
...  
Keyword(s):  
Amino Acids ◽  
Biological Activity ◽  
Absolute Configuration ◽  
Strong Dependence ◽  
Structural Similarity ◽  
Optically Active ◽  
Biologically Active ◽  
Chiral Molecules ◽  
Aminophosphonic Acid ◽  
The Past

Due to their structural similarity with natural α-amino acids, α-aminophosphonic acid derivatives are known biologically active molecules. In view of the relevance of tetrasubstituted carbons in nature and medicine and the strong dependence of the biological activity of chiral molecules into their absolute configuration, the synthesis of α-aminophosphonates bearing tetrasubstituted carbons in an asymmetric fashion has grown in interest in the past few decades. In the following lines, the existing literatures for the synthesis of optically active tetrasubstituted α-aminophosphonates are summarized, comprising diastereoselective and enantioselective approaches.

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.

Synthesis and characteristics of ethylenediamine-N,N'-di-S-α-isovalerate and isomers of its cobalt(III) complexes

1982 ◽  
Vol 47 (1) ◽  
pp. 210-216 ◽  
Author(s):  
Milan Strašák ◽  
František Bachratý ◽  
Jaroslav Majer
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Chemical Parameters ◽  
Methyl Group ◽  
Nmr Data ◽  
Physico Chemical ◽  
Natural Amino Acids ◽  
C Nmr

The synthesis and physico-chemical parameters are described of a new complexone based on natural amino acids, viz. ethylenediamine-N,N'-di-S-α-isovalerate (SS-EDDIV). 1H- and 13C-NMR data revealed that the methyl group in the substance are not equivalent. The isomers of the cobalt(III) complex with the asymmetric tetradentate SS-EDDIV ligand were prepared and separated; their characteristics are given. The absolute configuration of two of the five theoretically feasible isomers was determined based on their electronic absorption spectra and circular dichroism data.

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.

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