Sulfonyl halides reaction with aromatic

Both aromatic and aliphatic sulfonyl halides react with the iridium(I) complex (XI) to form octahedral S-bonded sulfinate derivatives such as (XLIX) 3S), These are characterized by intense infrared stretching frequencies centered near 1235 and 1065 cm , reminiscent of sulfones. The low frequencies of these absorptions suggest that the S-bonded sulfinate group is a strong ar-acid. Certain of the aromatic sulfinates eliminate SO2 upon heating, yielding iridium(III) aryls such as (L) 38). The scope of this gas-forming elimination reaction is uncertain. 

In the thermal reaction of aliphatic and aromatic sulfonyl chlorides with acetylenes no adduct has been observed82. However, the light-catalyzed additions of sulfonyl iodides to acetylenes83 as well as the thermal addition of sulfonyl bromides to phenylacetylene84 to form 1 1 adducts have been shown to be stereoselective and to occur in good to excellent yields. The fact that the addition occurs in a trans manner forced the authors83,84 to suggest that chain transfer by the sulfonyl halide (k ) is much faster than isomerization of the intermediate vinyl radical (k2) (see Scheme 5). 

Thiols can be prepared by the reduction of sulfonyl halides with LiAlHLj. UsualK the reaction is carried out on aromatic sulfonyl chlorides. Zinc and acetic acid, and... 

The replacement of a hydrogen atom on an aromatic nucleus by the sulfonyl halide grouping in a one-step process is accomplished by treat-ing the aromatic compound with chloro- or fluoro-sulfonic acid. Two equivalents of the halosulfonic acid are required, and frequently three equivalents are used. The aromatic sulfonic acid is presumably an intermediate in the process and is converted to the sulfonyl halide by the second equivalent of halosulfonic acid (cf. method 540). Reaction usually occurs at -5° to 30° in chloroform or carbon tetrachloride solution. 

Esters of aliphatic and aromatic sulfonic acids are conveniently prepared in high yields from alcohols and sulfonyl halides. A basic medium is required. By substituting sodium butoxide for sodium hydroxide in butanol, the yield of n-butyl p-toluenesulfonate is increased from 54% to 98%. Ethyl benzenesulfonate and nuclear-substituted derivatives carrying bromo, methoxyl, and nirro groups are prepared from the corresponding sulfonyl chlorides by treatment with sodium ethoxide in absolute ethanol the yields are 74-81%. Pyridine is by far the most popular basic medium for this reaction. Alcohols (C -Cjj) react at 0-10° in 80-90% yields, and various phenols can be converted to aryl sulfonates in this base. "... 

Some of these transformations were accompanied by additional reactions, e.g. formylation of the aromatic or heteroaromatic - nucleus or CH-acidic methyl groups further dehydration of amides to nitriles was observed. Adducts from amides and PCI3, sulfonyl halides or SO2CI2/SCXZI2 from which amidines can be obtained by reaction with amine derivatives (compare Section 2.7.2.5 and refs. 5 and 14) have not found wide application for this purpose. An interesting reaction is the preparation of the amidine (294 equation 158) from 7V-pentafluorophenylformamide. By thermal decomposition of the adducts from secondary amides and 7V,iV-dialkylcarbamoyl chlorides amidinium salts were synthesized from which the amidines (295 equation 159) were set free by treatment with bases. " ... 

As discussed in Section 3.06.5 aminothiazoles react with alkyl halides to give mainly the product of alkylation at the endocyclic nitrogen when the reaction is conducted in the absence of strong bases with acyl and sulfonyl halides, the exocyclic nitrogen becomes the main nucleophilic site. The reaction of 2-aminothiazoles with heterocyclic or aromatic aldehydes show ample differences depending on the various amine-aldehyde pairs <9lS62i>. In general the azomethine derivatives are obtained by a suitable procedure which has to be followed in each case. The increase of the amine/aldehyde ratio leads to bis-amines as the major products of the reaction. 

A standard condition has been optimized for this reaction, in which the aryl amine is diazotized in 10 times its amount of acetic acid, followed by the addition of one equivalent of cuprous halide in hydrohalic acid. Under these conditions, the acetate salt of aryl amine is relatively soluble, and less froth and tarry material are formed during diazo transformation. In addition, chlorination, bromination, and iodonation of p-haloaniline to dihalobenzenes under such standard conditions give almost comparable average yields. Other modifications of this reaction include the formation of phenyl selenocyanate by the reaction with potassium selenocyanate, and aryl nitrile by the reaction with nickel cyanide. Moreover, this reaction has been extended to the preparation of phenyl thiocyanate, phenyl isothiocyanate and aromatic sulfonyl chloride. ... 

In another approach, poly(aryl ether sulfones) were synthesized by the electrophilic Friedel-Crafts reactions of sulfonyl halides with aromatic hydrocarbons. The critical step in these polymerizations is the formation of the carbon-sulfur bond. High polymers were obtained, though they were not always completely linear. Carbonyl aryl carbon-carbon bonds are created in Friedel Craft reactions leading to poly(aryl ketones). 

Friedel-Crafts (and Other Aromatic Functionalization) Reactions. When treated with AgOTf, alkyl, acyl (eq 4), and sulfonyl halides are converted to extremely electrophilic triflate species that react rapidly with even deactivated aromatic rings in the absence of catalysis. Benzylic chloroformates participate similarly (eq 5). Aromatic rings are also efficiently vinylated and iodinated via AgOTf-promoted processes. 

Aromatic sulfonyl chlorides can be prepared directly, by treatment of aromatic rings with chlorosulfuric acid. ° Since sulfonic acids can also be prepared by the same reagent (11-7), it is likely that they are intermediates, being converted to the halides by excess chlorosulfuric acid. The reaction has also been effected with bromo-and fluorosulfuric acids. 

Diaryl sulfones can be formed by treatment of aromatic compounds with aryl sulfonyl chlorides and a Friedel-Crafts catalyst. This reaction is analogous to Friedel-Crafts acylation with carboxylic acid halides (11-14). In a better procedure, the aromatic compound is treated with an aryl sulfonic acid and P2O5 in polypho-sphoric acid. Still another method uses an arylsulfonic trifluoromethanesulfonic anhydride (ArS020S02CF3) (generated in situ from ArS02Br and CF3S03Ag) without a catalyst. ... 

A commonly used and important reaction of sulfonic acids, or sulfonates, is their conversion to sulfonyl chlorides by treatment with phosphorus halides, or sometimes with thionyl chloride. Although it is easy to postulate mechanisms for this conversion, the exact path followed has never been determined. Similarly, although mechanisms can be suggested for other known reactions involving sulfonic acids, such as the cleavage of dialkyl ethers by anhydrous sulfonic acids (Klamann and Weyerstahl, 1965), or the formation of sulfones by treatment of an aromatic hydrocarbon with a mixture of sulfonic acid plus polyphosphoric acid (Graybill, 1967), nothing truly definitive is known about the details of the actual mechanisms of these reactions. 

Sulfonylation of aromatic hydrocarbons in the presence of a Lewis acid and the reaction of sodium benzenesulfinate with alkyl halides proved to be particularly easy and useful to prepare starting materials for the Julia olefination procedure (see Section 4.3.2). 

Polysulfonylation. The polysulfonylation route to aromatic sulfone polymers was developed independently by Minnesota Mining and Manufacturing (3M) and by Imperial Chemical Industries (ICI) at about the same time (81). In the polymerization step, sulfone links are formed by reaction of an aromatic sulfonyl chloride with a second aromatic ring. The reaction is similar to the Friedel-Crafts acylation reaction. The key to development of sulfonylation as a polymerization process was the discovery that, unlike the acylation reaction which requires equimolar amounts of aluminum chloride or other strong Lewis acids, sulfonylation can be accomplished with only catalytic amounts of certain halides, eg, FeQ3, SbQ, and InCl3. The reaction is a typical electrophilic substitution by an arylsulfonium cation (eq. 13). 

Mesylates are used for Ni-catalysed reactions. Arenediazodium salts 2 are very reactive pseudohalides undergoing facile oxidative addition to Pd(0). They are more easily available than aryl iodides or triflates. Also, acyl (aroyl) halides 4 and aroyl anhydrides 5 behave as pseudohalides after decarbonylation under certain conditions. Sulfonyl chlorides 6 react with evolution of SO2. Allylic halides are reactive, but their reactions via 7t-allyl complexes are treated in Chapter 4. Based on the reactions of those pseudohalides, several benzene derivatives such as aniline, phenol, benzoic acid and benzenesulfonic acid can be used for the reaction, in addition to phenyl halides. In Scheme 3.1, reactions of benzene as a parent ring compound are summarized. Needless to say, the reactions can be extended to various aromatic compounds including heteroaromatic compounds whenever their halides and pseudohalides are available. 

The Friedel-Crafts sulfonylation of aromatics with alkane- and arenesulfonyl halides and anhydrides has been studied (Eq. 9) [23]. In the reaction of pentafluorobenzenesul-fonyl fluoride with pentafluorobenzene, decafluorodiphenyl sulfone is formed with deca-fluorodiphenyl [23c]. Certain phenylacetylenes react with SO2 and benzene in the presence of SbFs to form benzothiophene 5-oxide [24]. (Eq. 10). Sulfinyl fluoride reacts similarly with arenes under SbFs catalysis to give sulfoxides (Eq. 11) [25]. 

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