Pyridines sulphuryl chloride

The value of the second-order rate constant for nitration of benzene-sulphonic acid in anhydrous sulphuric acid varies with the concentration of the aromatic substrate and with that of additives such as nitromethane and sulphuryl chloride. The effect seems to depend on the total concentration of non-electrolyte, moderate values of which (up to about 0-5 mol 1 ) depress the rate constant. More substantial concentrations of non-electrolytes can cause marked rate enhancements in this medium. Added hydrogen sulphate salts or bases such as pyridine... 

Chlorination of steroid ketones has been studied in only a few cases. The reaction with elementary chlorine [iS ] is generally similar to bromination, but other sources of electrophilic chlorine have also been used. These include sulphuryl chloride, pyridine hydrochloride perchloride, and tert-butyl hypochlorite [J57]. 

Synthesis of Phosphoric Acids and their Derivatives.-New approaches to the preparation of dialkyl phosphorofluoridates include the treatment of a vinyl phosphate, e.g.,(l), or an irninophosphace, e.g.,(2), with triethylamine tris(hydrogen fluoride) when the alkyl group consists of a suitably protected nucleoside, the reaction between mono(crimethylsilyl) phosphite in pyridine and sulphuryl chloride fluoride at -30° has been successfully explored. Dibenzyl phosphorofluorldate, hitherto unreported, has been obtained from tecrabenzyl diphosphate and caesium fluoride, and also from the reaction between dibenzyl hydrogen phosphate and 2-fluoro-N-methylpyridinlum tosylate. ... 

Selected hydroxyls in sucrose can be replaced by chloride by exploiting reactions with either sulphuryl chloride in pyridine (11) or mesyl chloride in D.M.P. (12,13). The reaction with sulphuryl chloride involves the initial formation of a chlorosulphate ester (N) which then undergoes an intramolecular nucleophilTc substitution reaction with the insertion of chloride. 

Under controlled conditions, sucrose reacts with sulphuryl chloride in pyridine in a highly selective manner to give either 6,6 -dichloro-6,6 dideoxysucrose... 

A synthesis of 2-alkyl- or 2-aryl-substituted benzo[Z>]thiophens consists of the cyclization of an aryl thioether with an acetonyl or phenacyl group in the or/Ao-position (315) with 48% hydrobromic acid. In order to obtain (315 R = Ph), 2-methylthiobenzyl cyanide is treated with phenyl-magnesium bromide. The reaction of or//to-methylthiostyrene derivatives, especially cinnamic acids (316), with sulphuryl chloride followed by pyridine, probably gives the benzo[6]thiophens (318) via the sulphenyl chloride (317). ... 

A series of 3-deoxy compounds derived from methyl a-o-glucopyranoside were obtained via iV,iV-dimethylsulphamoyl esters which underwent efficient reductive cleavage on treatment with sodium in liquid ammonia under conditions in which acetal, ester, acetamide, and azido groups were stable. The required esters were prepared by use of V,A-dimethylsulphamoyl chloride, or with sulphuryl chloride in pyridine, followed by dimethylamine. Other... 

A series of three papers has described the reactions of 2-acyloxyisobutyryl chlorides with nucleosides (particularly cytidine) to give 3 - and 3, 5 -acylated 2,2 -anhydro-jS-D-arabinofuranosyl-nucleosides, which can be converted into the corresponding l-/3-D-arabinofuranosyl-nucleotides with either aqueous pyridine or sodium carbonate-sodium hydrogen carbonate in aqueous /j-dioxan. 2,2 -Anhydro-5-chloro-l-(5-chloro-5-deoxy-jS-D-arabinofuranosyl)cytosine was obtained on treatment of cytidine with sulphuryl chloride in acetonitrile similarly, 1- -D-arabinofuranosylcytosinegave2,2 -anhydro-5-chloro-l-(5-chloro-5-deoxy-j3-D-... 

Treating a thiophenol, formaldehyde, and an amide with phosphorus trichloride in pyridine provides a new process for the synthesis of 2 -1,3-benzothiazines (343). On treatment with sulphuryl chloride in methylene chloride at room temperature, appropriately substituted benzothiazolines gave 1,4-benzothiazines in high yield (Scheme 149). Rearrangement of 2-phenacyl-l,2-benzisothiazolin-3-one... 

Bobrdnski io showed that pyridine 1-oxide hydrochloride reacted at 120° with sulphuryl chloride, giving 2- and 4-chloropyridine (the former predominating) and a trace of pentachloropyridine. The reaction has been repeated" and applied to substituted pyridine 1-oxides""2, 9H. 3-Bromo-pyridine 1-oxide gave 3-bromo-4-chloro-, 3-bromo-2-chloro- and 3-bromo-6-chloro-pyridine, in that order of yields, but overall a-substitution outweighed y-substitution 8. The reaction with 3,5-diethoxypyridine 1-oxide seems to be the only one reported in which chlorination was not accompanied by loss of the oxide function782. 

Examples are the 2-substitution and loss of the oxide function in the reaction between pyridine, acetic anhydride and ethyl cyanoacetate (p. 206), and the chlorination of pyridine 1-oxides with sulphuryl chloride, though in the latter example the mechanistic necessity for loss of the oxide function is not established. Quaternary salts of pyridine oxides react at C(2) with Grignard reagents and alkoxide ion is eliminated (p. 201), but in the related reaction with cyanide, ion substitution at both C(2) and C(4) can occur (p. 225). 

The reaction of 6-0-acetylsucrose with sulphuryl chloride in chloroform/pyridine gave, after dechlorosulphation and acetylation, a mixture of (19) and (20). The chlorine atoms at C-4 in these compounds were postulated to be derived from the chloride ion opening of the isomeric C-3, epoxides. Compound (20), after... 

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