Fused pyridine ring

Azonia substitution at a naphthalene bridgehead position gives the quinolizinium ion (16). Oxonia substitution, elsewhere, forms the 1- and 2-benzopyrylium ions (17) and (18). The two most well-known monoaza systems with three aromatie fused rings are aeridine (19), derived structurally from anthraeene, and phenanthridine (20), an azaphenanthrene. The better-known diaza systems inelude phenazine (21) and 1,10-phenanthroline (22), while systems with three linearly fused pyridine rings are ealled anthyridines, e.g. the 1,9,10-isomer (23). 

Another approach involves utilization of the amines for addition of a fused pyridine ring to the benzothiadiazole skeleton. The Gould-Jacobs reaction of 4-amino-2,l,3-benzothiadiazole 60 with diethyl ethoxymethylenemalonate gave the substitution product, and, after thermal cyclization in diphenyl ether, afforded the... 

After reduction of the nitro function of the porphyrin, the porphyrinamine intermediate can be reacted with z./l-unsaturated carbonyl compounds to yield porphyrins with a fused pyridine ring, which is formed by Michael addition, imine formation and dehydrogenation. 

In a paper concerned with the synthesis of fused pyridazines, the isoxazole 13 was used as a masked amino alcohol, which was eventually used to construct a fused pyridine ring. A standard hydrazine reaction, followed by hydrogenolysis of the isoxazole of the intermediate... 

With the exception of furopyridines, there have been no extensive studies using 13C NMR spectroscopy of these compounds. There is, however, a considerable volume of information concerning the, 3C NMR data for furopyridines <91JHC1469>. Table 23 lists l3C NMR data for the parent compounds and some simple derivatives. Based on analysis of the 13C NMR data, the C-2 and C-3 shifts are very similar to those for furan, indicating that the fused pyridine ring has minimal electronic effect upon those carbon atoms. Carbon-13 NMR data for a series of furodipyridines... 

An intramolecular reaction of an isocyanate on a benzo[l, 2-b 4,3-6 ]difuran constructed a fused pyridine ring, probably via a pericyclic reaction <86JHC1637>. Photolysis of the bisthiadiazoloquinone... 

The most well-known monoaza aromatic systems with three six-membered rings are acridine 25 and phenanthridine 26 (Figure 3). Acridine derivatives were among the earliest antibacterial agents. The better known diaza systems include phenazine 27 and 1,10-phenanthroline 28. Systems with three linearly fused pyridine rings are called anthyr-idines, e.g., 29. A derivative of the tetraza ring system 30 is found in vitamin B2. 

Fused pyridine rings, polymeric hydrocyanic acid ... 

In the present review, an analysis is made of the synthesis and properties of six isomeric heterocyclic systems containing two fused pyridine rings with different mutual arrangements of nitrogen atoms - naphthyridines (pyridopyridines, diaza-naphthalenes). They include two groups of compounds - V(l),V(7)-naphthyridines (i — 5, 6, 7, 8) 1-4 and V(2),V(/)-naphthyridines (J — 6, 7) 5, 6. 

The pyridine ring is fused at bond a of the acridine. Depending on the position of the nitrogen in the fused pyridine ring, four different types of pyrido[fl]acridines are possible. 

Volume 70 of Advances in Heterocyclic Chemistry consists of three chapters together with the Subject Index for Volumes 61 through 70. The first contribution by Dr. Istvan Hermecz (Chinoin, Hungary) continues with Part II of his set of three chapters on condensed pyridines. Part I, in Volume 69, covered pyrido[l,2-ft][l,2]oxazines, -thiazines, and -pyridazines, and the present chapter deals with [l,2-c]-fused 1,3-oxanes, 1,2-thiazines, and -pyrimidines. The third part will appear in a subsequent volume of our series and will deal with 1,4-oxazines and 1,4-thiazines, fused pyridine rings. 

Thermolysis of an azido-aldehydc can produce a fused pyridine ring in high yield. 

A nitrovinyl-iminophosphorane may be cyclized to a fused pyridine ring by heating it in toluene for about 12 h with an isocyanate yields are usually very good. 

Amino-azoles or -azines react with 1,3-dicarbonyl compounds in the presence of a mild base [2361] or an acid [2088] to give a fused pyridine ring. 

Thermally induced annulation of neighbouring acetyl and enamino groups with ammonium acetate in DMF can be a very effective method of building a fused pyridine ring. 

The 1,3-oxazinone (87.6) is a partly cyclic acetal the EtO group is displaced by reaction with a conjugated diene in the presence of boron trifluoride a fused pyridine ring is formed. 

Polyheteroaromatic systems containing a fused pyridine ring are susceptible to partial hydrogenation, with the pyridine ring the site of attack. The following examples involve lA and 3,3 -bis(9-phenanthrenyl)-BINOL IB. ... 

A further study examined fused pyridine rings, in quinoline and acridine, as tethered templates [53]. Although the chlorine atom complex might have had a different structure... 

A few alkaloids are derived from carbazole, e.g. murrayanine 1 (l-methoxycarbazole-3-carbaldehyde) and ellipticine 2, which is a carbazole system with a fused pyridine ring. Ellipticine is one of the substances which can intercalate into human DNA. The molecule is inserted between two paired bases. Ellipticine derivatives are approved in some countries for use as cytostatic agents [59]. 

Several methods that employ the opening of a variety of side-chain or fused pyridine ring systems have been developed for the synthesis of side-chain acids and derivatives. An interesting example is the ring opening of... 

ABSTRACT. A series of macrocyclic ligands related to hexaaza[is]-annulene form stable complexes with alkali metal and alkaline earth ions. A planar, substituent-solubilized "torand", consisting of multiply fused pyridine rings, has been synthesized and has been found to sequester calcium from a dilute source. 

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