Amino vicinal effect

Vicinal effects can also play a part in the course of the reaction utilizing Oppenauer conditions. 1,3-Diols or j5-amino alcohols may not react, presumably on account of format on of an aluminum complex. If oxida-... 

Vicinal effects can also play a part in the course of the reaction utilizing Oppenauer conditions. 1,3-Diols or / -amino alcohols may not react, presumably on account of formation of an aluminum complex.5 5 46b> If oxidation were to take place it would probably be followed by dehydration to give an unsaturated ketone. Retro-aldol cleavage has been found to occur with a 17,21-dihydroxy steroid.32 The 11 -hydroxyl group which is generally inert to Oppenauer oxidation will react if a hydroxyl group is present on the... 

Additivity of Circular Dichroism of d—d Transitions The Vicinal Effect in a Homologous Series of Triethylenetetraaminecobalt(IH) Amino Acid Complexes... 

This report describes a method of experimentally obtaining the vicinal effects of amino acid anions bound to a tetraamine-cobalt(III) moiety by dealing exclusively with A-B2 complexes of both R and S-amino acids. Additivity of circular dichroism of both the configurational and vicinal effects for - transitions is verified experimentally. It is demonstrated that the vicinal effect not only contains information as to the chirality of the bound amino acid but also as to the mode of binding, i.e., Bi vs. b2-... 

Matsuoka et al. isolated and characterized geometrical isomers of [Co(am)2-(en)]" " and [Co(am)2(ox)] type complexes (am = amino-acidate) in order to investigate a vicinal effect displayed by the coordinated optically active a-amino-acidate. 

Yasui et al. (1965 Yasui, 1965) studied the CD spectra of copper-amino acid complexes in more detail and showed that copper complexes with l-amino acids in water exhibit four Cotton effects in the region of the d-d absorption band positive at 830 and 730 nm and negative at 635 and 565 nm. The CD curves of the complexes of proline, hydroxyproline, and histidine are considerably different from those of other amino acid complexes for which the main CD band at ca. 630 nm shows the opposite positive Cotton effect. It was suggested that the vicinal effect of the asymmetric a-carbon atom is stronger than that of the asymmetric j -carbon atom (L-threonine and L-allothreonine) and thus determines the sign of the Cotton effects. 

Yasui et al found that the CD curve in the first band region for a series of typical optically active amino acid complex ions of the type [Co(NH3)4(aa)] (aa = amino acid anion) were of the same form as reported for the vicinal effect of optically active amino acids in complex ions of the type [Co(en)2(aa)] (Fig. 1). Cyclic amino acids and some others gave different types of CD curves. The CD curves for vicinal effects are also of the same type for some isomers of [Co trien(aa)] complex ions, vide infra. The combination of such an effect with the configurational contribution can account for the appearance of one or two CD peaks in the first band region for complex ions of the [Co(en)2aa] type without assuming a change in frequency interval for the two transitions. 

The hydrophilic hormones are derived from amino acids, or are peptides and proteins composed of amino acids. Hormones with endocrine effects are synthesized in glandular cells and stored there in vesicles until they are released. As they are easily soluble, they do not need carrier proteins for transport in the blood. They bind on the plasma membrane of the target cells to receptors that pass the hormonal signal on (signal transduction see p.384). Several hormones in this group have paracrine effects—i.e., they only act in the immediate vicinity of their site of synthesis (see p. 372). 

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