Pyridine and Related Systems

V. PYRIDINE AND RELATED SYSTEMS A. Bi- and Terpyridine-Based Materials... 

Method A has a very wide application and was used to prepare various derivatives of 1 and related systems, such as quinoline, isoquinoline, and cyclopentano[/)]pyri-dine (pyridine). 

Pyridines and related nitrogen heterocyclic (azabenzenoid) compounds Polyfluoroaromatic nitrogen heterocyclic systems are all activated, relative to the corresponding benzenoid compounds, towards nucleophilic aromatic substitution. The magnitude of this activation is illustrated by the effects of a ring nitrogen, relative to C—F at the same position, for attack by ammonia [91] (Figure 9.32). 

A variety of pyridine ring syntheses stem from Vilsmeier formylation of alkenes, enamines, vinyl ethers, ketones, and related systems followed by a separate cyclization of the derived salts with ammonium chloride or acetate.49... 

One Nitrogen Atom (it is self-subdivided into Pyridines, Pyridinium Compounds, Ylides, Pyridine N-Oxides, Applications of Pyridines, Bipyridines and Related Systems, Hydropyridines, Biologically Active Pyridines and Hydropyridines, Pyridines Annulated with Carbocycles, Pyridines Annulated with Heterocycles). 

Six-membered Systems with One Heteroatom 10.3.4.1 Synthesis of Pyridines and Related Compounds... 

Pyrido[2,3-d]imidazo[2,l-b]thiazolo[5y4-b]pyridine (CsNS-CsNi-CsN-CsN) and Related Systems.—The readily available 2-chIoro-3-isothiocyanatopyridine (284) reacts with compounds containing both electrophilic and nucleophilic centres to form a variety of condensed thiazolopyridines. Its interaction with aminoacetonitrile, for example, furnishes 56% yields of 1-amino-imidazo[2,l-b]thiazolo[5,4-b]pyridine (285). Its condensation with methyl-... 

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