Naming fused heterocycles

The ancient Egyptians used the plantAmmi majus, which contains methoxsalen (sometimes called 8-methoxypsoralen, based on a now obsolete method of naming fused heterocycles indexed in Chemical Abstracts under furo[3,2-g][l]benzopyran-7-one, 9-methoxy-, 249), in combination with sunbathing to... 

Both purine and pteridine are parent heterocycles for nomenclature purposes. The systematic procedure for naming fused heterocycles is an extension of that we saw in Section 11.8 where we considered a benzene ring fused to a heterocycle. The main difference is that we have to identify bonds in two... 

The naming of benzo-fusee heterocycle is discussed in Section 1.2,... 

Pyrano-fused heterocycles, namely pyrano[3,2-f]quinoline-2,5(6//)-diones, pyrano[3,2-f]benzopyran-2,5(6//)-dione, and pyrano[3,2-f]pyridine-2,5(67T)-diones, have been efficiently prepared by the condensation of 4-hydroxy-2-(l//)-quinolines, 4-hydroxycoumarin, or 4-hydroxy-(17/)-pyridone with a-acetyl-y-butyrolactone or the sodium salt of a-formyl-y-butyro-lactone in the presence of ammonium acetate <1999JHC467>. 

The benzo[a] (19), benzo[/t (15) and benzo[c] (16) fused heterocycles are heterocyclic analogues of naphthalene, with the dibenzo heterocycles (17) bearing a similar electronic relationship to phenanthrene. Some of these compounds are still known by their trivial names indole (15 Z = NH), isoindole (16 Z = NH), carbazole (18) and indolizine (19). The names thianaphthene and pyrrocoline for (15 Z = S) and (19) respectively are now little used. Particular confusion can arise in consulting... 

IUPAC/Chemical Abstracts System (IUPAC Rule B-3). The fusion operations described in Section II, A, 3, a are applied to trivial and/or Hantzsch-Widman names of heterocyclic (and, if present, car-bocyclic) components see examples 25-27. In addition a unit consisting of a benzene ring fused to a one-ring heterocycle can be considered as a single component. If this one-ring heterocycle contains 3-10 members it... 

This illustrates the correct way of naming a ketone derivative of a partially unsaturated fused heterocycle as far as determining the mode of citation of the degree of hydrogenation is concerned, the parent is structure a, not b [which could yield incorrect names such as 4,4,7,9-tetrabromo-2,3,4,5-tetrahydro- H-l-benzazepin-5-one or 4,4,7,9-tetra-bromo-2,3-dihydro-l//-l-benzazepin-5(4/f)-one] (IUPAC Rule C-315). 

The majority of reported reactions of aryl and heteroaryl substrates with organocopper reagents are examples of Stephens-Castro coupling or the more recent catalytic version of that reaction. The reaction has found recent application in syntheses of C-(6)-substituted pterins and pteridines, substituted pyridines, and the antitumor antibiotic fredericamycin A," to name a few. Aryl iodide can be che-mospecifically displaced in the presence of bromide," and 2,5-dibromopyridine is regioselectively substituted at the 2-position. Substitution of halobenzenes by propargyl alcohol, followed by oxidative cleavage, provides a convenient route to terminal arylalkynes. " Fused heterocycles are formed in reactions of aryl halides bearing nucleophilic ortho substituents. - "... 

The confusion that can arise when the formula of a relatively simple fused heterocycle is wrongly drawn may be illustrated with a tricyclic compound which may be drawn in several ways, some of which are shown in (1,8) to (1.12). None of these is in accord with lUPAC recommendations (1.13) is the correct formula and is the one that should be used. Peripheral numbering of this compound is shown and its name is pyrazinol2, 3 4.5]thieno[3,2-[Pg.21]

Aromatic polycychc compounds need not contain contain benzene rings. For example, purine, which contains two fused heterocyclic rings, is aromatic. Azulene, named for its deep blue color, is also aromatic, although one ring has five carbon atoms and the other has seven. It is not, however, as aromatic as its isomer naphthalene, which has two fused benzene rings. 

This is the first attempt to review all fused heterocyclic systems (6 6 6) containing at least one ring junction heteroatom. There are three classes of these systems, namely heterocyclic analogues of anthracene, phenanthrene, and phenalene, which are surveyed in Tables 1-3 respectively. Please... 

Systems in which at least two neighbouring atoms are common to two or more rings are known as fused systems. For several bicyclic benzo-fused heterocycles, trivial names are permitted, e.g. ... 

The fused P-lactams 36 and 37, the fused oxazolidinones 38 and 39, [intermediates in Danishefsky s synthesis of staurosporine (see Chapter 24)], 41 and a precursor to this, namely 40, ° and 42. The X-ray structure of d-mannose derived azepine 43 shows this to adopt a pseudo-chair conformation. The glucose-based tetrazole 44 and fused heterocycle 45. ... 

In yet another classification, they can be broadly classified into three classes namely Aromatic polyamides or Aramides like Kevler, Twaron, etc., Aromatic heterocyclic and Aromatic copolyesters (Pegoretti and Traina 2009). Aromatic heterocyclic LCPs are kind of lyotropic liquid crystal containing wholly aromatic molecular framework with fused heterocyclic ring along the main chain. Aromatic copolyesters exhibit thermotropic behavior and are characterized by high... 

Provided that no retained trivial name is applicable, fused heterocyclic systems are given Hantzsch-Widman names. Fusion of components follows the same pattern as established for corresponding hydrocarbons and an intricate series of seniority rules must be run through for selecting the parent component. Traditional abbreviated terms are retained for the following fusion components furo, imidazo, (iso)quino, pyrimido, thieno. 

The major internal comparisons to be made within this chapter are between (13) pyrrole (1), furan (2), thiophene (3), selenophene (4) and tellurophene (5) b) pyrrole (1) and indole (6) (c) indole (6), benzo[6 Jfuran (7) and benzo[6]thiophene (8) d) indole (6), isoindole (9) and indolizine (10) and (e) benzo[6] and benzo[c] fused systems. The names of relevant heterocyclic radicals are given with the structures of the parent heterocycle. 

The fusion of four membered-heterocycles with two heteroatoms onto face a of the quinoline offers two isomeric combinations of the tricyclic ring system l,2-heterocyclo[2,3-a]quinoline and l,3-heterocyclo[3,2-a]quinoline. The later one of these two ring systems is the only one that examples of it namely, l,3-thiazeto[3,2-a]quinoline have been reported. Moreover, examples of those fused on faces ij or j are not known (Fig. 3). 

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