Glycine complexes Subject

These solutions of Cd are powerful reducing agents, and after tens of microseconds all Cd has disappeared. If Cd complexes of such ligands as glycine, en, EDTA and NT A are subjected to pulse radiolysis, the Cd produced is present as a complex ... 

Metal-ion catalysis has been extensively reviewed (Martell, 1968 Bender, 1971). It appears that metal ions will not affect ester hydrolysis reactions unless there is a second co-ordination site in the molecule in addition to the carbonyl group. Hence, hydrolysis of the usual types of esters is not catadysed by metal ions, but hydrolysis of amino-acid esters is subject to catalysis, presumably by polarization of the carbonyl group (KroU, 1952). Cobalt (II), copper (II), and manganese (II) ions promote hydrolysis of glycine ethyl ester at pH 7-3-7-9 and 25°, conditions under which it is otherwise quite stable (Kroll, 1952). The rate constants have maximum values when the ratio of metal ion to ester concentration is unity. Consequently, the most active species is a 1 1 complex. The rate constant increases with the ability of the metal ion to complex with 2unines. The scheme of equation (30) was postulated. The rate of hydrolysis of glycine ethyl... 

Another approach employing chiral acyclic azomethine ylides was published in two recent papers by Alcaide et al. (85,86). The azomethine ylide-silver complex (51) was formed in situ by reaction of the formyl-substituted chiral azetidinone (50) with glycine (or alanine) in the presence of AgOTf and a base (Scheme 12.18). Azomethine ylides formed in this manner were subjected to reaction with various electron-deficient alkenes. One example of this is the reaction with nitrostyrene, as illustrated in Scheme 12.18 (86). The reaction is proposed to proceed via a two step tandem Michael-Henry process in which the products 52a and 52b are isolated in a... 

The complexation of the Group IIB metals by amino-acid and related derivatives continues to be a subject of interest stability constants reported include those for histidine and its derivatives, histamine, glycylhistamine, aspartic and glutamic acids, aspargine, glutamine, glycine, cysteine, and alanine. " ... 

For testing nutrition by means of simple amino-adds described above, we have utilized a very complex mixture which greatly resembles the natural products of the hydrolysis of peptones. Most of the substances entering into this mixture have been studied separately, espedally from the point of view of the influence which each may exert on the assimilation of the whole. It has been attempted experimentally to see whether all the products of hydrolysis are indispensable, or whether they can be replaced by each other. Although these tests are very delicate and are diflflcult to perform, they have nevertheless given definite results. Glycin appears to play an entirely secondary part and another add can be substituted for it. On the contrary, tryptophane appears to be a substance that is absolutely necessary. The following is an experiment on this subject ... 

Numerous azobenzenes and imines have been used to prepare cyclopalladated ctmiplexes, and the liquid crystal properties of some of die products have been investigated. 1 Cyclometallated derivatives have also been prepared from 2-phenylpyiidines, > 2,6-diphenylpyridine, 6-phenyl bipy. O and 6-(2-thienyl) bipy.509 Other substrates subjected to cyclopalladation include amidines, thio- and selenoamides, ll> l N-phenylsulftmyl glycine, hydroxyquinoline derivatives, the drugs diazepam and prazepam, and PBu 3. Doubly cyclopalladated complexes have been prepared from 1,3-diacetylbenzene dioxime and also from N,N-dialkyl benzene-l,3-dicarbaldimines. The 2D NMR spectra of cyclopalladated 8-methylquinoline and benzo-(h)-quinoline show that a CH bond occupies a fifth coordination position above the square plane.520... 

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