Reactions thionyl chloride

Other heterocyclic systems prepared by a thionyl chloride reaction include fused thiazoles,71 thiatriazoles,72 oxathiins,73 and dithiins 74 some further examples are given in reviews.53... 

Analysis of the reaction products showed that the boron content was nearly equimolar to the chloride content after reaction with thionyl chloride. About twice this amount of aluminum was retained by the samples, however. Since the presence of unchanged aluminum chloride could not entirely be ruled out, the balance of aluminum versus chloride was established. From the chloride deficit was substracted the number of silanol groups as determined by the thionyl chloride reaction. This difference was ascribed to molecular water. About one molecule of free water was found for each two silanol groups in the temperature range of 100 to 350°. The sample treated with BCI3 contained considerably less... 

The equivalence of sulfur and oxygen in this ring system carries over to NSAIDs as well. Preparation of the sulfur analogue of isoxepac (6-4) starts with the alkylation of thiophenol (27-1) with benzyl chloride (26-1). Cyclization of the intermediate thioether (27-2) then affords the homothioxanthone (27-3). The carboxyl side chain is then extended by means of the Amdt-Eistert homologation reaction. The acid is thus hrst converted to its acid chloride by means of thionyl chloride. Reaction with excess diazomethane leads to the diazoketone (27-4). Treatment of that intermediate with silver benzoate and triethylamine leads the ketone to rearrange to an acetic acid. There is thus obtained tiopinac (27-5) [28]. 

Hydrazides 59 can be cyclized by phosphoryl chloride,72 thionyl chloride,79 boiling phenol,80 by heating in the corresponding acid or acid chloride,81 by lead tetraacetate,82 or by heat.83 The thionyl chloride reaction goes via the thioxadiazolone. 

The thionyl chloride reaction apparently can proceed from the alkyl chlorosulfite stage by more than one mechanism an ionic SN2 chain reaction with chloride ion,... 

Fig. Intermediate in the thionyl chloride reaction to form an acid...

Fig. Mechanism for the thionyl chloride reaction with a carboxylic acid to form an acid chloride.

Propose a mechanism for the reaction of benzoic acid with oxalyl chloride. This mechanism begins like the thionyl chloride reaction, to give a reactive mixed anhydride. Nucleophilic acyl substitution by chloride ion gives a tetrahedral intermediate that eliminates a leaving group, which then fragments into carbon dioxide, carbon monoxide, and chloride ion. 

The use of ether as solvent for thionyl chloride reactions apparently suppresses reactions by trapping hydrogen chloride in a non-ionic form, so that no Cl ions are available in solution [ig]. In certain aliphatic allylic alcohols solvent changes can have a profound effect on product composition, but no comparable data are available for steroid reactions. 

The sequence for preparing the hydroxyketone started by conversion of the acid 15-1 to its chloride with thionyl chloride. Reaction of that acid halide with diazomethane gives the diazoketone 15-2. The hydroxyl group at C3 is then oxidized to the corresponding ketone by means of an Oppenauer reaction. Treatment of the product 15-3 with gaseous hydrogen chloride replaces nitrogen in that intermediate by chlorine. Displacement of chlorine by acetate then leads to the 21-acetate 15-5. Saponification of the ester completes the sequence. 

The synthesis of the second fragment, the oleandrose disaccharide appendage, is outlined in Scheme 94 [206,207]. The sequence begins with the addition of vinylmagnesium bromide to 689, which produces a 5 1 mixture of diastereomeric alcohols 700. Without separation, these are quantitatively converted to the cyclic sulfite 701 upon deprotection and treatment of the resulting diols with thionyl chloride. Reaction of 701 with diiron pentacarbonyl under ultrasonic conditions produces a mixture of diastereomeric iron complexes which, when carbonylated at 230 atm, gives j5,y-unsaturated lactone 702. 

Dimethylformamide/thionyl chloride Reactions with dimethylchloroformiminium chloride ... 

The thionyl chloride reaction (37) is once again a convenient method for attaching chemically and electrochemically active groups to electrode surfaces. 

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