Synthesis diaryl sulfones

Abbady MA, Hebbachy R (1993) Synthesis and application of some symmetrical and unsymmetrical diaryl sulfides and diaryl sulfones containing pyrazolinyl and isoxazolinyl moieties. Indian J Chem Sect B 32 1119-1124... 

Aryl sulfones have been prepared from sulfinic acid salts, aryl iodides and Formation of thiocyanates from unactivated aryl halides has been accomplished with charcoal supported copper(l) thiocyanate. " The copper catalyzed reaction of Na02SMe and aryl iodides give the aryl methyl sulfone. " A similar synthesis of diaryl sulfones has been reported using a palladium catalyst. " ... 

Sulfinate anions have been used as nucleophiles in palladium-catalyzed allylic alkylation [143]. More recently, both Cu- and Pd-catalyzed couplings of sulfinate anions with aryl halides have also been reported as a means to generate unsymmetrical diaryl sulfones, which are common motifs in bioactive molecules [38, 93, 144—148]. Similarly, Cu-catalyzed coupling of arylboronic acids with sulfinate anions has been reported [95,149,150]. Notably, Kantam and co-workers found that the use of ionic liquids permits Cu(OAc)2-catalyzed sulfone synthesis at ambient temperature and with convenient product separation and catalyst recyclability (17) [150]. 

Several examples of S-arylation of sulfides and P-arylation of phosphines using diaryliodonium salts were reported in the older literature [877,878]. These reactions generally proceed by a radical chain mechanism. The arylation of phosphines has been used to promote the photo-initiation of cationic polymerization [879]. More recently, the synthesis of diaryl sulfones via S-arylation of sodium arenesulfinates, ArS02Na, by diaryliodonium salts has been reported [880]. 

In the synthesis of arylsulfonyl chlorides, it is generally preferable to add the aromatic substrate gradually to the excess of chlorosulfonic acid rather than the other way about. Under these conditions, the reagent is mostly present in a large excess during the reaction which minimizes the formation of both the diaryl sulfone and the arylsulfonic acid. With highly reactive substrates, an inert solvent is used and the reaction temperature must be carefully controlled and kept as low as feasible to avoid unwanted di- and trisulfonation. ... 

While much of the chemistry described previously was focused on the synthesis of sulfides and related compounds, a range of diaryl sulfones can also be generated through... 

SCHEME 545 Ruthenium-catalyzed synthesis of diaryl sulfones [67]. 

A transition metal-free approach to the synthesis of diaryl sulfones has been devised using diaryliodonium salts (Scheme 5.48) [70]. The reactions were carried out in DMF at 90 °C and afforded high yields of the diaryl sulfones. A vast array of electron-donating and electron-withdrawing groups were well tolerated by this approach as well as heteroaromatic compounds. One of the strengths of this approach was the ability to functionalize extremely bulky substrates. As an example, sodium 2,4,6-triisopropylphenyl sulfuiate was arylated in 61% yield. If a metal-free synthesis is needed for the synthesis of an unsynunet-rical diaryl sulfone, this chemistry would be a reasonable approach. 

Head-to-tail dimerization of thiocarbonyl compounds to 1,3-dithietanes (Scheme 105) occurs thermally <1977JOC2345> and photochemically <1981JOC3911>, or catalyzed either by a base <1973T2759> or a sulfonic acid <1997BCJ509>. For example, synthesis of dithietane 213 in excellent yield was performed by the room temperature dimerization of the thione 212 (Scheme 106) <2004TL7655, CHEC-III(2.18.4.2)838>. Diaryl thioke-tones are resistant to dimerization. Some thiones dimerize to 1,3-dithietanes <1975BSF(2)1670>. 

A variation on the aromatic nucleophlic displacement chemistry described above employs the cuprous chloride catalyzed polycondensation of an aromatic dihydroxy compound with a divalent aromatic dibromo diaryl compound. This method has the advantage that the dibromo diaryl compound does not have to be activated by the sulfone group. This route can therefore be employed for copolymers and ter-polymers that incorporate the sulfone moiety along with other non-sulfone-containing repeat units. This synthesis route is commonly known as the Ullmann sjmthesis [4]. 

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