Pyridyl sulphones

The oxidation of pyridine thiols can give several sorts of compound, but reagents such as nitric and chromic acids, and potassium permanganate, convert some pyridine-2- and -4-thiols into hydroxypyridines 213, 769 The formation of 2-methoxypyridines from methanolic ammonia and methyl 2-pyridyl sulphones has also been observed 3. A few cases are known of the conversion of pyridine-2- and -4-sulphonic acids into hy-... 

H. Diehl and G. F. Smith, The Iron Reagents — Bathophenanthroline, Batho-phenanthroline Sulphonic Acid, 2,4,6-Tripyridyl-s-triazine, Phenyl-2-pyridyl Ketox-ime. Smith Chem. Co., Columbus, Ohio, 1965. 

The (Z)-6-heterocyclylmethylene penam sulphones were shown to be effective 5-lactamase inhibitors and potent ampicillin and cefazolin potentiators against both Gram-positive and Gram-negative yff-lactamase producing bacteria [79]. In particular, several of these analogues having a r-deficient 2-heteroaryl substituent attached to the C-6 methylene positon, such as the 6-(2-pyridyl)methylene derivative (28), displayed exceptional activity. In combination with ampicillin or cefazolin they exhibited... 

A mechanism of action for the r-deficient 2-heteroaryl derivatives was postulated based upon the reaction of 6-(2-pyridyl)methylene penicillanic acid sulphone (28) with sodium methoxide (Scheme 6.14) [46]. Chen and co-workers proposed that after bimolecular interaction between the enzyme and (28), an aromatic acyl-enzyme ester (76) is obtained. This conjugated... 

Triaza-Compounds. 2-(Ethoxymethyleneamino)pyridine is converted into the triazolopyridine (564) by the action of hydroxylamine-O-sulphonic acid. Anodic oxidation of the hydrazone Ar NHN=CHAr (Ar =p-NO2C6H4, Ar = /7-MeC6H4) in the presence of pyridine and tetraethyl-ammonium perchlorate affords the salt (565). Oxidative cyclization of the pyridylhydrazone PyCH=NNHPy (Py = 2-pyridyl) by means of mercury(II) acetate yields compound (566). 2,4,6-Triphenylpyrylium fluoroborate reacts with amidrazones ArC(NH2)=NNH2 in the presence of triethylamine to give the pyrazolopyrimidines (567). The tricyclic compound (568) is... 

More interestingly, electron transfer reaction of cytochrome c and other redox proteins occurs with fast rates at modified electrodes. The most efficient electrode surface promoters tend to be bifunctional molecules containing surface-active functional groups (thiol, disulphide, or pyridyl) which bind the promoter to the electrode surface and weakly basic or anionic functional groups (such as pyridyl nitrogen, carboxy-late, sulphonate or phosphate) which can bind the positively charged cytochrome c [188-190,204-211]. For instance, if a gold electrode is modified with 4,4 -bipyridine, this promoter forms a monolayer at the... 

Electron Diffraction.—Among completed electron-diffraction studies are ethyl methyl sulphide, chloromethyl methyl sulphide, methyl phenyl sulphide, di-(2-pyridyl) sulphide, sulphones, sulphoxides and sulphones, and trifluoro-methanesulphonyl chloride. A number of precise analyses of gas-phase conformational equilibria have emerged. Methyl ethyl sulphide shows a preference for the gauche conformation rather than for the trans form. ... 

Bromine converts pyridine-3-sulphonic acfd, in boiling aqueous solution, into 4-amino-3,5-dibromopyridine, presumably through 3,4,5-tribromo-pyridine and a derived 3,5-dibromo-4-pyridyl-pyridinium salt (see p. 266)159, 160. 

The reactions of pyridine 1-oxides with / -toluenesulphonyl chloride have produced complicated results . From pyridine 1-oxide a small amount of 3-pyridyl / -toluenesulphonate resulted, and 3-methylpyridine 1-oxide gave some 3-(5-methylpyridyl) / -toluenesulphonate, but a number of other substances were also formed. The 3-substituted pyridines have been represented as arising from an initial nucleophilic attack by chloride ion, and studies with labelled j -toluenesulphonyl chloride show that the subsequent step cannot involve a free sulphonate ion but may go through an... 

In the heterocyclic field, sulphur substitutions include the sulphonation of quinoline to produce mainly the 8-acid, plus the 5-, 6-, and 7-acids, the chlorosulphonation of 2-(3,4-dicholorophenyl)- and 2-(3-pyridyl)-imidazole (on the imidazole ring) and of 2-(4-chlorophenyl)imidazole on both aromatic rings, the tosylation at N-3 of some 2-(monosubstituted amino)-l,3,4-thiadiazoles (which isomerise to products that are sulphonylated on the exocyclic nitrogen), and the thiolation of 2-methylindolizine with diaryl disulphides to form (53). ... 

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