A-Hydroxypyridine

The acyl derivatives of A-hydroxypyridine-2-thione are a synthetically versatile source of free radicals. These eompounds are readily prepared from reactive acylating agents, sueh as acyl chlorides, and a salt of A-hydroxypyridine-2-thione ... 

Aminyl radicals are produced by the sequence outlined in equation 114. The action of phosgene on the sodium salt of A-hydroxypyridine-2-thione yields the salt 326, which reacts with amines to give 327. The latter decompose to the radicals 328 on heating or irradiation380. 

The esters of A-hydroxypyridine-2-thione are another versatile source of radicals.195 The radical is formed by decarboxylation of an adduct formed by attack at sulfur by the... 

A very efficient methodology for generating carbon radicals utilizes esters of A-hydroxypyridine-2-thione as radical precursors, and these have been used by Blood-... 

E. Aminyl Radicals from A -Hydroxypyridine-2(l//)thione Carbamates. 11... 

In a-hydroxypyridine (Fig. 3), which exists mainly in the pyridone structure, the elimination of CO is the predominating cleavage re-... 

Decarboxylation of the aliphatic esters of A-hydroxypyridine-2-thione by tributyltin hydride leads to reduction of the radical and the formation of the alkane lacking the carboxyl carbon, as in the Barton-McCombie reaction (Scheme 3.61). 

Cortinarius species usually grow in semimountain-ous and deciduous forests at the end of the summer or in autumn, and may be easily mistaken for the Psylocybe genus, the so-called "magic mushrooms" appreciated by drug-abuser people for its hallucinogenic properties. The toxicity of Cortinarius is related to the orellanine toxin, a hydroxypyridine with structural analogy to paraquat, which blocks protein synthesis and induces oxidative stress [88,89]. Numerous cases of orellanine-induced nephrotoxicity have been reported in Europe (C, orellanus and C, speciosissimus) [90-92], North America and Canada [88] and suspected in 3 patients in Australia [93]. 

Studies of the generation of hydroxyl radicals by photocleavage of the N-O bonds in A -hydroxypyridine-2(1 0-thione, and N-hydroxy-2(l//)-pyridone have been reported. Alternative photochemical sources of hydroxyl radicals are 4-mercaptopyridine-A -oxides. ... 

Barton has devised such a pathway for converting carboxylic acids to hydroperoxides via A -hydroxypyridine-2-thione esters [16a,b] (Scheme 5). The yields of hydroperoxides are 45-89% [16]. Reduction of the crude products with trimethyl phosphite (rt) or dimethyl sulfide (80 °C) readily provides the corresponding alcohols. On the other hand, tosylation and ensuing Kornblum-De La Mare type fragmentation [17] leads to carbonyl compounds [16b] (Scheme 5). 

When 2- or 4-aminopyridine is diazotized, a-pyridone or y-pyridone is formed. Apparently, the diazonium salt reacts immediately with water to form a hydroxypyri-dine (Section 16.10). The product of the reaction is a pyridone because the keto form of a hydroxypyridine is more stable than the enol form. (The mechanism for the conversion of a primary amino group into a diazonium group is shown in Section 16.12). 

The dehydrogenation of jervine and of iso jervine yields 2-ethyl-5-methylpyridine as well as a hydroxypyridine, CsHuON, which is regarded as 3-hydroxy-2-ethyl-5-methylpyridine (31, 41). 

A2a7b1a. Bipyridyl derivatives A2a7b1 b. a-Hydroxypyridine ethers A2a7b1c. Pyridines A2a7b2. Two nitrogen atoms... 

Methyl fluorosulfonate 2,6-Dicyanopyridines from 3-a-hydroxypyridine N-oxides... 

Related Reagents. A -Hydroxypyridine-2-thione 4-Methyl-3-hydroxythiazole-2-thione 5-(/ Methoxyphenyl)-4-methyl-3-hydroxythiazole-2-thione (Diacetoxyiodo)benzene AAHydroxy-phthalimide. 

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