Fused Heterocyclic Rings

A wide variety of such derivatives is known. The mutual influence of heterocyclic rings in them is as expected from their electronic nature and number of heteroatoms. However, some unique reactions 

8 REACTIVITY OF SUBSTITUENTS ATTACHED TO RING NITROGEN ATOMS 

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Hydrazino groups are also converted into H-compounds with mercury(II) oxide (74CR(C)-(278)427) in other reactions they have given hydrazones, or have been converted into pyrazoles and fused heterocyclic rings (77JAP(K)7785194), e.g. (72) -> (73). 

Diazepines alkylation, 7, 617 electrophilic reactions, 7, 615 with fused heterocyclic rings... 

Aromatic macrocycles, flat hydrophobic molecules composed of fused, heterocyclic rings, such as ethidium bromide, acridine orange, and actinomycin D... 

G. Amino Group as Part, of a Fused Heterocyclic Ring. . . 426... 

Structure of tropones, tropolones, and tropylium salts with fused heterocyclic rings 95AHC(64)81. 

Lipophilicity and specific hydrophobic surface area were determined by using reversed-phase thin-layer chromatography for fused heterocyclic ring systems including five pyrido[2,iy][l,2,4]triazine derivatives <1998MI64>. 

As is now common practice, H NMR spectra (NMR - nuclear magnetic resonance) have been recorded on most examples of the fused heterocyclic rings mentioned in later sections in this chapter, and as such the primary literature is replete with the data for these and should be consulted directly. 

Table 2 Fused heterocyclic ring systems (6 5 6) with two ring junction heteroatoms...

A general approach to the synthesis of (6 5 6) fused heterocyclic ring systems involves intramolecular cyclization of two substituents attached to a five-membered ring of the fused (6 5) system. A typical example is cyclization of 211 to... 

All synthetic references are printed in boldface in Tables 1-3. The synthetic methods reported have been classified below into several general approaches according to a one-pot construction of one, two, and three fused heterocyclic ring systems. 

As shown in Figure 1, the onset of decomposition temperature was in this order polybenzoxazole ) 2,4-DIF-PMTAI> 2,4-DIF-PMI. The char yield of these polymers followed the same sequence. It showed that the introduction of more fused heterocyclic rings into the backbone of the polymers enhanced the thermal stability and flame resistance of polymeric materials. 

Tropones, Tropolones, and Tropylium Salts with Fused Heterocyclic Rings Part I Synthesis ... 

A number of synthetic methods are useful for tropoids fused to different heterocyclic rings. These will be comprehensively treated in Sections II,A and II,C, where preference is given structurally simple examples. Sections II,B and II,D, respectively, will contain special synthetic paths to individual fused heterocyclic rings. 

From Other Seven-Membered-Ring Compounds with Fused Heterocyclic Rings... 

The synthesis of tropones, tropolones, and tropylium salts with fused heterocyclic rings forms the first part of a projected two-chapter sequence by G. Fischer (Leipzig, Germany). It is planned that the structure, reactivity, and applications of these compounds will be discussed in a further contribution in a subsequent volume. 

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