Nitrogen heterocycles, literature

There are conflicting generalizations in the heterocyclic literature as to the relative reactivity of a- and y-positions in azines toward nucleophiles. Variations in the relative reactivity are attributed in this and subsequent sections to specific factors operating in addition to activation by azine-nitrogen. Another possible source of variation may be a decrease in selectivity with increasing reactivity of one or both reagents, an effect established in electrophilic aromatic... 

A review was published this year covering the literature of saturated nitrogen heterocycles over 1998 with a section devoted to piperidine synthesis <99JCS(P1)2553>. 

There are a considerable number of such syntheses in the literature. Most of the syntheses are based on the reaction of two equivalents of isocyanate with a nitrogen heterocycle. The two examples given are typical of the route (equation 103 and Scheme 107). The mechanism of formation of the l,3,4-oxadiazolo[3,2-a][l,3,5]triazine-5,7-diones (175) is included as it is of interest (74T221, 74JCS(P1)1786). 

Undoubtedly, pyridine, C5H5N (2), is the best-known heterocyclic nitrogen ligand and its coordination chemistry has been studied in great detail, as have its simple derivatives bearing a non-coordinating substituent. For the physical properties, the reader is referred to the heterocyclic literature.1 3,5,9 The basic properties of pyridine have been mentioned above. Alkyl-substituted derivatives are slightly more basic [pA (base) values of about 5-7]. 

The nitrogen heterocyclic analogs of quinones, azaquinones, are interesting heterocyclic compounds, but have received only limited attention. In fact, 2-aza-3-phenyl-1,4-naphthoquinone is one of the first examples in the literature (69HCA1810 71TL1621). There are several examples of other hydroxylated derivatives that can exist in several tautomeric forms, and no evidence has been presented that unambiguously establishes which... 

There now exists a vast literature on inorganic heterocycles, and much of this has been reviewed in the two recent volumes edited by Haiduc and Sowerby [19], The most extensively studied of the boron-nitrogen heterocycles, and probably the system... 

Although the chemistry of the polycyclic nitrogen heterocycles containing one heteronitrogen atom has been the subject of many comprehensive reviews in recent years, the chemistry of pyrindines has received no such attention.la-lb This review will systematically survey the chemical literature, through 1969, concerning the chemistry of the derivatives of 1-pyrindine (l)-(9), 6,7-dihydro-5//-l-pyrindine (10), hydroxy- and oxo-6,7-dihydro-5//-l-pyrindine, 5/7-l-pyrindine-5,7(6/7)-dione (11), and hexahydro- and octahydro-1-pyrindine. Some medically important 1 -pyrindine derivatives, such as the octahydro- and decahy-drobenzo[a]cyclopenta[/]quinolizines (12) and (13) will also be discussed. 

Aran, Goya, and Ochoa (Institute of Medicinal Chemistry, Madrid, Spain) contribute the first comprehensive review of heterocycles containing the sulfamide moiety, covering a wide diversity of heterocyclic ring systems. The chapter by Comins and O Connor, on regioselective substitution in aromatic six-membered nitrogen heterocycles, describes exciting work contributed by their laboratory and also includes a broad literature survey. 

AO has been shown to be responsible for the primary metabolism of several drugs that contain an aromatic nitrogen heterocycle [72,88,159,160]. In general, when drug structures contain aromatic nitrogen heterocycles, a role for AO should be considered in preclinical and in vitro tests. The contribution of this enzyme to drug clearance can be defined by examining metabolism of an NCE by cytosolic preparations and inhibition by either menadione or raloxifene [161, 162], DDIs with AO have not yet been reported in the literature. 

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