3-(2′-Chloroethyl)-2-methyl-3,4-dihydroquinazolin-4-one ( I ) was reacted with sodio (sodium thioglycolate) in dry dioxane and yielded compound II . By using thionyl chloride, this compound was converted to the corresponding acid chloride ( III ). The prepared acyl chloride ( III ) was allowed to interact with different α-amino acids such as Gly, L -Ala, L -B-Phe, DL -Asp, L -Glu, L -Thr and L -Val to give new amino acid derivatives ( IVa – g ). A selected C-terminal derivative of glycine ( IVa ) was converted into acid chloride ( V ). The acid chloride formed was reacted with L -Ala, L -B-Phe, DL -Asp, L -Glu, L -Thr and L -Val and yielded the new dipeptides VIa – f . The structures of the synthesized compounds were elucidated by elemental analysis and IR spectra. The prepared peptides were tested for their antimicrobial activities by comparison with tetra-cycline as a reference compound. 相似文献
An electrochemical method was used to measure the mean activity coefficients of amino acids in water‐electrolyte‐amino acid systems. The amino acids were glycine, DL‐serine and DL‐valine and the electrolytes were KNO3 and NaNO3. The activity coefficients of the electrolytes were obtained from the e.m.f measurements in an electrochemical cell with an anion and a cation ion‐selective electrodes, each measured versus a double junction reference electrode at 298.15 K. The activity coefficients of the amino acids in the ternary systems were obtained from those of the electrolyte according to the cross differential relation. A simple semi‐empirical model based on a modification of a more complex form, derived from perturbation theory, was used to correlate the activity coefficients in binary aqueous solutions and in ternary systems. 相似文献
A new multipurpose glycine equivalent for the general asymmetric synthesis of α‐amino acids is introduced. The chiral reagent can be transformed to various amino acids by alkylations with alkyl halides as well as aldol and Michael addition reactions under operationally convenient reaction conditions at room temperature with virtually complete stereochemical control.
Nonproteinogenic α- or β-amino acids have attracted tremendous attention, as they are widely utilized for biological, biochemical, pharmaceutical, and asymmetric chemical investigations. Recently, we developed a series of new strategies for preparing achiral and chiral nickel(ii) complexes for the synthesis of amino acids. We applied these new methods utilizing chiral nickel(ii) complexes for the asymmetric Mannich reaction to synthesize enantiopure α,β-diamino acids, the enantioselective tandem conjugate addition-elimination reaction to prepare glutamic acid derivatives, the Suzuki coupling reaction to yield β(2)-amino acid derivatives, the asymmetric Mannich reaction to synthesize 3-aminoaspartate, the asymmetric Michael addition reaction to give β-substituted-α,γ-diaminobutyric acid derivatives, the asymmetric alkylation reaction to prepare linear ω-trifluoromethyl containing amino acids, and the asymmetric Michael addition reaction to synthesize syn-β-substituted tryptophans. 相似文献
