- Improved synthesis of trans-4-alkylcyclohexane carboxylic acids
-
Several stereomerically pure amino acid derivatives containing the N-terminal trans-4-alkylcyclohexanoyl fragment were obtained. Hydrogenation of 4-alkylbenzoic acids in the presence of a special Ru-Ni/C catalytic system and isomerization of the resulting mixture of trans- and cis-isomers of 4-alkylcyclohexanecarboxylic acids were used as the key steps. The stereomeric configuration of all compounds was confirmed by 1H NMR spectroscopy. The compounds obtained possess a broad biological activity potential and are useful intermediates in the synthesis of stereomerically pure modified peptides.
- Bazurin, Alexey A.,Krasnikov, Sergey V.,Obuchova, Tatiana A.,Danilova, Angelina S.,Balakin, Konstantin V.
-
p. 6669 - 6672
(2007/10/03)
-
- Epimerization of 2- or 4- substituted cyclohexanecarboxylic acids
-
The present invention relates to a new method for obtaining a purity of about 93% to 100% of the trans form of 2- or 4-substituted cyclohexanecarboxylic acid or reactive derivatives thereof from the cis form or a mixture of the cis and trans forms by a single step, particularly, to a method for obtaining a purity of substantially 100% of the trans form of 4-substituted cyclohexanecarboxylic acid.
- -
-
-
- Synthesis of Mesogenic Compounds, Catalyzed by Metal Complexes. II. A New Method of Synthesis of 4,4'-Dialkylbiphenyls
-
A new method for the synthesis of 4,4'-dialkylbiphenyls containing both n-alkyl- and 4-trans-n-alkylcyclohexyl substituents, based on highly selective reactions of monoalkylation and monoacylation of 1,4-dibromobenzene in the presence of palladium complexes is developed.
- Bumagin, N. A.,Luzikova, E. V.,Beletskaya, I. P.
-
p. 1487 - 1491
(2007/10/03)
-
- Synthesis and Liquid Crystalline Phases of Pyridazine Derivatives II
-
Four more pyridazine compounds were synthesized.The compounds have a general structure R-X-Y-Z-R'; where Y is 3,6 disubstituted pyridazine ring, X and Z are either trans cyclohexyl or phenyl rings, R and R' are n-alkyl groups.The structure assignments were confirmed by carbon 13 NMR.Their liquid crystalline properties were evaluated.When both X and Z are cyclohexyl rings, the compounds have a single smectic b phase.However, if a phenyl ring is introduced into the system, the morphology becomes complicated.Keywords: synthesis, pyridazine, smectic, classification
- Liang, Jason C.,Cross, Julie O.
-
p. 235 - 244
(2007/10/02)
-
- ISOMERIZATION UNDER THE INFLUENCE OF p-TOLUENESULFONIC ACID.
-
The authors have investigated the influence of a mild acid isomerization catalyst, p-toluenesulfonic acid (TSA), on 4-butyl- (Ia) and 4-hexyl- (Ib) cyclohexanecarboxylic acids and their methyl esters (IIa, IIb). It is found that p-toluenesulfonic acid is an effective catalyst of cis-trans isomerization of 4-alkylcyclohexanecarboxylic acids and their esters; removal of water from the reaction medium raises the isomerization rate. Esters of alkylcyclohexanecarboxylic acids are isomerized at higher rates than the acids themselves. A probable mechanism of the acid-catalyzed isomerization reaction is proposed.
- Kovshev,Karamysheva,Torgova,Geivandova,Roitman
-
p. 1069 - 1070
(2007/10/02)
-