Exotic Amino Acids. Part 1. Synthesis of α-Amino Acids with a Cyclohexene Substituent.-A new method for the preparation of the exotic, i.e unnatural, title amino acids (VI) (6 examples) from ylidene derivatives of Meldrum acid (I) using a cycloaddition-amination-Hofmann rearrangement strategy is developed. -(ZITSANE, D. R.; RAVINYA, I. T.; RIIKURE, I. A.; TETERE, Z. F.; GUDRINIETSE, E. YU.; KALEI, U. O.; Russ.
Exotic Aminoacids. Part 2. Reaction of 2-R-4-Methylcyclohex-4ene-1,1-isopropylidenemalonates with Some O-and N-Nucleophiles. -Reaction of the title cyclohexene-isopropylidenemalonates (I) with Oor N-nucleophiles proceeds with dioxane ring opening to furnish derivatives of cyclohexenemono-or -dicarboxylic acids depending on the basicity of the nucleophile and on the reaction temperature. -(ZITSANE, D. R.; RAVINYA, I. T.; RIIKURE, I. A.; TETERE, Z. F.; GUDRINIETSE, E. YU.; KALEI, U. O.; Russ.
aminocarboxylic acidsaminocarboxylic acids (hydrazinocarboxylic acids) and esters (acyclic compounds) P 0270
-084Exotic Amino Acids.Part 4. Synthesis of Methyl Esters of Some N-Heteroaminomethylenemalonic Acids.-Isopropylidene N-hetarylaminomethylenemalonates (III), obtained from the corresponding ethoxymethylenemalonates (I) and amino-substituted heterocycles (II), undergo methanolysis to give the corresponding N-hetarylaminomalonates (V). N-hetarylaminomethylenemalonate, containing a 2-aminothiazole group as a heterocyclic substituent, does not react under analogous conditions, but cyclizes upon heating to give thiazolopyrimidinecarboxylic acid (VI). 4-Oxopyridinopyrimidines (VII) are obtained upon sublimation of compounds (III). -(ZICANE, D.; RAVINYA, I.; TETERE, Z.; RIJKURE, I.; GUDRINIECE, E.; KALEJS, U.; Chem. Heterocycl.
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