2-(9-Xanthylmethyl)-2-(2′-carboxycyclopropyl) glycine 6e is a novel metabotropic glutamate receptor antagonist. A series of alpha, C-3′ disubstituted (carboxycyclopropyl)glycines 6f-n were prepared. Antagonist activity was observed for all these compounds at group 2 and group 3 mGluRs. Although they were slightly less active on group 2 mGluRs than non C-3′ substituted 6e, the compounds 6f-n were more selective with lesser or no activity on group 1 mGluR subtypes (IC50 values greater than 100μm).

New conformationally restricted glutamate analogues 2-(3′-alkyl-2′-carboxycyclopropyl)glycines (1a-c and 2a-c) were enantioselectively prepared by the addition-elimination reaction of the chiral lithium bislactim ether anion of 3 to racemic 4-alkyl-4-bromobut-2-enoates.

Measurements of gill dimensions were carried out on two ecologically distinct active rheophilic teleost species, the curvina Plagioscion squamosissimus and the curimbatá Prochilodus scrofa , and were analysed in relation to body mass according to the equation Y=aW b . The gill respiratory areas of P. squamosissimus and P. scrofa were large as expected for active fish and increased with increasing body mass ( b =0.70 and 0.72, respectively) showing no significant difference between them. However, the large respiratory area of both species was realized in a different way revealing an adaptation to the plasticity of head components related to feeding habits. Consequently, significant differences were found between the number and average length of gill filaments and the bilateral area of secondary lamellae. The respiratory area of P. scrofa was due mainly to larger bilateral surface area of the secondary lamellae and its growth coefficient ( b =0.51) that was significantly higher ( P <0.05) than that found for P. squamosissimus ( b = 0.36). The frequency of secondary lamellae mm −1 of filament was similar in both species (22 ± 2 on one side of gill filament). The dimensions of gill components and the respiratory area of these species suggest a complex interaction between head form, and feeding habits related to the functional morphology of the gills to meet the oxygen requirements of each species.

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The enantiomerically pure glycine derivative tert-butyl (S)-2-(tert-butyl)-3-methyl-4-oxo-1-imidazolidinecarboxylate (Boc-BMI) reacts with (Z)-1,4-dichloro-2-butene and 3-chloro-2-(chloromethyl)-1-propene to give the bicyclic intermediates 5 and 6, respectively. These dialkylated systems are hydrolyzed to the corresponding heterocyclic alpha-amino acids (S)-baikiain (L-4,5-didehydropipecolic acid) and (S)-4-methylene proline which are obtained in 96 and 90% ee, respectively. (C) 1997 Elsevier Science Ltd.

Monoepoxydienes 1, derived from acyclic and cyclic conjugated dienes, react under neutral conditions with the benzophenone imine of glycine nitrile 4 in the presence of a catalytic amount of Pd(PPh3)4 (5% mol) to afford the corresponding unsaturated 6-hydroxy substituted α-amino acids 5 in a regio (1,4-addition) and stereoselective manner. However, the benzophenone imine of glycine ethyl ester 2 only react with butadiene monoepoxide to furnish regio and stereoselectively ethyl (4E)-6-hydroxy-2-(diphenylmethylene)amino-4-hexenoate (3) a precursor of a bulgecinine diastereomer.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The reaction of lithium enolate derived from benzophenone imine of glycine ethyl ester 1 with allylic dihalides 2 in the presence of a catalytic amount of Pd(Ph3)4 (5% mol) affords the corresponding bis(imino esters) 3. Subsequent hydrolysis of compounds 3 gives the corresponding bis (α-amino acids) 4. This methododology has been used to synthesise α,α’-diaminosuberic acid.

The Mukaiyama and Palomo reagents have been used for the kinetic resolution of racemic carboxylic acids or alcohols with homochiral alcohols or carboxylic acids, respectively, in the presence of triethylamine. Thus, enantiomerically enriched carboxylic acids (e.e.<68%), alcohols (e.e.<41%) or diastereoisomerically enriched esters (d.e.<84%) are obtained.