Catecholic chemistry

J.S. Thomson and J.C. Calabrese, Copper-catechol chemistry. Synthesis, spectroscopy, and structure of... 

Employing catechol chemistry, a novel family of biodegradable and strong wet-tissue adhesives, iCMBAs, was developed in our lab by introducing dopamine into the pendent groups of PEGC [22,23]. iCMBAs are superior to... 

In the case of anachelin, it is possible to observe how one of the general limitations of catechol chemistry (its low stability toward oxidation, especially at elevated pH) is circumvented by the introduction of the electron-wididrawing dimediyl-ammonium group, bound to die aromatic ring of die catechol To die same end, we have introduced die nitro (—NO2) group in the para-position to die hydroxide, due to synthetic ease and relatively small additional steric bulk. ... 

The close electrochemical relationship of the simple quinones, (2) and (3), with hydroquinone (1,4-benzenediol) (4) and catechol (1,2-benzenediol) (5), respectively, has proven useful in ways extending beyond their offering an attractive synthetic route. Photographic developers and dye syntheses often involve (4) or its derivatives (10). Biochemists have found much interest in the interaction of mercaptans and amino acids with various compounds related to (3). The reversible redox couple formed in many such examples and the frequendy observed quinonoid chemistry make it difficult to avoid a discussion of the aromatic reduction products of quinones (see Hydroquinone, resorcinol, and catechol). 

See also E. Haslam, Protection of Phenols and Catechols, in Protective Groups in Organic Chemistry, J. F. W. McOmie, Ed., Plenum Press, New York and London, 1973. pp. 145-182. 

Catechol is also obtained from coal coking and from certain wood residues. Vanillin (synthetic vanilla flavoring) is a catechol derivative. Resorcinol and hydroquinone are currently made by the same type of chemistry used... 

FIGURE 9.29 Transformation of 2-halogenated benzoates to catechol by concomitant decarboxylation and dehalogenation. (From Neilson, A.H. and Allard, A.-S., The Handbook of Environmental Chemistry, Vol. 3R, Springer Verlag, 2002, pp. 1-74. With permission.)... 

Alkylcatechols are important as chemicals and chemical intermediates in the fine chemistry industry for the synthesis of flavouring agents, agricultural chemicals and pharmaceuticals [1]. 3-methyl catechol has a special value from the industrial point of view. Previously y-alumina was found to be an effective catalyst for the gas-phase methylation of catechol with methanol [2]. The process can be schematically presented as ... 

Goss, C.H.A., Henderson, W., Wilkins, A.L. and Evans, C. (2003) Synthesis, characterisation and biological activity of gold(lll) catecholate and related complexes. Journal of Organometallic Chemistry, 679, 194. 

The chemistry of most of the drugs in this family is quite simple, accounting in part for the very large number of analogues which have been made. The foundation for the chemistry in this series was laid long ago by Stolz in his classic synthesis of the ophthalmic agent adrenal one (3) in which he reacted catechol with chloroacetyl chloride and then displaced the reactive chlorine atom with methylamine to complete the synthesis. Borohydride reduction would have given epinephrine (adrenaline). 

A brief overview on why most of the autoxidation reactions develop complicated kinetic patterns is given in Section II. A preliminary survey of the literature revealed that the majority of autoxidation studies were published on a small number of substrates such as L-ascor-bic acid, catechols, cysteine and sulfite ions. The results for each of these substrates will be discussed in a separate section. Results on other metal ion mediated autoxidation reactions are collected in Section VII. In recent years, non-linear kinetic features were discovered in some systems containing dioxygen. These reactions form the basis of a new exciting domain of autoxidation chemistry and will be covered in Section VIII. 

There has been enormous activity in the field of copper(I)-dioxygen chemistry in the last 25 years, with our information coming from both biochemical-biophysical studies and to a very important extent from coordination chemistry. This has resulted in the structural and spectroscopic characterization of a large number of copper dioxygen complexes, some of which are represented in Figure 14.2. The complex F, first characterized in a synthetic system was subsequently established to be present in oxy-haemocyanin, and is found in derivatives of tyrosinase and catechol oxidase, implying its involvement in aromatic hydroxylations in both enzymes and chemical systems. 

The same comparison was made for hydroquinone for a given conversion of 80%, which is exhibited in Fig. 12.8. Unlike catechol and 3-methycatechol, products resulting from hydroquinone cracking in the presence and absence of iron oxide are identical. A peak found at m/z 110 is probably hydroquinone and its fragment ions are at m/z 39, 55, and 81. The identities of some of the products (Fig. 12.8a and b) are likely to be as follow acetylene (m/z 26), vinyl acetylene (m/z 52), butadiene (m/z 54), cyclopentadienone (m/z 80), and 1,4-benzoquinone (m/z 108). To confirm the differences in chemistry between catechols and hydroquinones, 2,3-dimethyhydroquinone was subjected to the same comparison. 

Figure 12.9 shows the products distribution generated from 2,3-dimethyl-hydroquinone cracking with 80% conversion under two different thermal conditions. Despite its two substituted methyl groups, it followed the same trend as found with hydroquinone, i.e. the product distributions were identical in both cases, which again was different from the chemistry of catechol. A peak of the starting material is found at m/z 136 (dimethylbenzoquinone) and possible identities of other peaks are methylpen-tenyne (m/z 80) and butadiene (m/z 54). 

This range is for tripodal ligands - a log value of about 59 has been estimated for the Fe + complex of an encapsulating tris-catecholate ligand (Vogtle, F. Supramolecular Chemistry -, Wiley Chichester, 1991, Section 2.3.7.)-... 

In fluorine-18 chemistry some enzymatic transformations of compounds already labelled with fluorine-18 have been reported the synthesis of 6-[ F] fluoro-L-DOPA from 4-[ F]catechol by jS-tyrosinase [241], the separation of racemic mixtures of p F]fluoroaromatic amino acids by L-amino acylase [242] and the preparation of the coenzyme uridine diphospho-2-deoxy-2-p F]fluoro-a-o-glucose from [ F]FDG-1-phosphate by UDP-glucose pyrophosphorylase [243]. In living nature compounds exhibiting a carbon-fluorine bond are very rare. 

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