Polyheterocyclics containing

Polyheterocyclics containing sulfur are also of interest. Poly(2,5-thienylene) can be prepared as a light green powder by electrochemical oxidahve coupling. In the neutral state, this compound has o 10 " S cm", but on exposure to Ij, the conductivity is raised to o 10 S cm". Of particular interest in this group is poly(isothianaphthalene)... 

Pyrazolopyridopyrimidine-containing polyheterocycles have been prepared by two routes, by formation of either the six- or the five-membered ring this is illustrated by the two syntheses of compound 469 (Scheme 106)... 

Several polyheterocyclic compounds containing a condensed 1,2,4-triazole nucleus, such as 3,5-disubstituted thiazolo [2,3-r][ 1,2,4] triazoles, are thermostabilizers for polypropylene and polycaproamide <2003MI2>. Triazolo[3,4-A][l,3]benzothiazoledicarbonitrile derivatives are used to prepare hexazocyclanes-fluorophores as active media for liquid and solid lasers, scintillators, and for transformation of short-wave radiation to long-wave radiation <2004RUP2238276>. 

The reaction of vinyl isocyanates of type 123 with enamines gives intermediates containing the enaminoamide moiety, which subsequently undergoes an intramolecular cyclization and affords phenanthridine derivatives (84JOC4569). Numerous polyheterocycles were synthesized similarly (89JOC224). 

Recently, interest in the syntheses of polyheterocyclic systems containing fused l,3-thiazin-4-ones has been growing due to the search of new biologically active substances. The synthetic methods used for obtaining these compounds are the same as those used for benzo-TAs. 

A series of dyestuffs have been reported which contain the pyrido[2,3-p]-l,2,4-triazine and pyrido[4,3-e]-1,2,4-triazine nuclei. These compounds have been used to dye a number of fibres fluorescent yellow shades <74GEP(0)2417916>. Another series of polyheterocyclic dyestuffs which contain a pyridotriazine moiety have been patented as fast yellow dyes especially for synthetic fibres <75GEP(0)2355967>. Amongst a number of the compounds prepared as dyestuffs were several 1H-pyrido-l,3,4-thiadiazines. The compounds were used to dye polyester fibres fast shades of yellow <77USP4025510>. 

A polyheterocyclic chain of degree of polymerization / can be attacked by the acii e centre at a heteroatom of any originally monomeric unit. The members describing this type reaction must therefore be multiplied by the factor (j — I), or(/ — i). when the monomer contains a single susceptible heteroatom. The described approach is permissible only when all heteroatoms in the chain are sterically equally accessible. 

The synthesis of heterocycles via rDA processes includes the preparation of heterocycles with two different heteroatoms. Furo[3,4-c]pyridine (218), a previously unknown polyheterocyclic, has beat achieved by FVP of adduct (217) (equation 98). The heteropentalene Aieno[3,4-6]fuian (220) has been synthesized by a reaction pathway based upon rDA formation of polyheterocycle (219) (equation 99). Other heterocycles prepared via rDA reactions that contain two differoit heteroatoms include 6H-l,3-oxazin-6-one (221) and 3-arylisoxazoles (222). ... 

Polyheterocycles can even be made by polymer analogous reactions. A good example of this is the formation of oxadiazole-containing polymers. Thus, Janietz et al. [86] prepared the precursor polymers 89 by the polycondensation of 90 with 91 and then dehydrated it with phosphorus oychloride to give the phenylene oxadiazole copolymers 69 (Scheme 6.21). 

Mercaptobenzothiazole (2-) A nitrogen- and sulfur-containing polyheterocyclic organic thiol used as vulcanization accelerator for rubber. Requires zinc oxide as an activator. Its vulcanizates have a good aging resistance. A yellowish powder with distinctive odor. Combustible. Also called MET. 

As a main conclusion of this work, a summary of the influence of the vinyl groups on the electronic properties of the parent polymers is presented in Fig. 6. The same trends are observed, when changing the heteroatom, for the ionization potential and the energy bandgap of polyheterocycles and poly (heteroaromatic vinylenes). A continuous decrease of IP and increase of Eg are obtained on going from sulfur to oxygen-containing polymers and from... 

Fused polyheterocycles are also often present in active natural products like those depicted in Figure 6.7. In the previous section, few examples of efficient synthesis of this kind of molecules, containing indole in their structure, have been shown. Some further instances of spiroin-doline preparation will be compiled in the section of dedicated to spiro-type polyheterocyclic compounds (Section 6.4.3). 

Fused Systems containing Thiazole.—A large number of polyheterocyclic systems have been prepared, but in most cases the methods of synthesis, and the properties of the products, are straightforward extensions of earlier work they will not, therefore, be further discussed. 

So, M., Liu, Y, Ho, C., et al. (2011). Silica-Supported Gold Nanoparticles Catalyzed One-Pot, Tandem Aerobic Oxidative Cyclization Reaction for Nitrogen-Containing Polyheterocyclic Compounds, Chemcatchem, 3, pp. 386-393. 

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