Diaryl sulfides, from

Interaction of substituted arenediazonium salts with potassium O. O-diphenylphosphorodithioates gave a series of solid diazonium salts which decomposed explosively when heated dry [10], The unique failure of diazotised anthranilic acid solutions to produce any explosive sulfide derivatives under a variety of conditions has been investigated and discussed [6]. Preparation of diaryl sulfides from interaction of diazonium and thiophenoxide salts led to violent explosions, attributed to presence of some arenediazo sulfide during subsequent distillation of the diaryl sulfides. Precautions are detailed [11]. A safe method of preparation of diaryl sulfides from diazonium tetralluoroborates and sodium benzenethiolate in DMF is now available [12],... 

An excellent preparation of diaryl sulfides from aryl iodides and arenethiolate ions has been devised. Photolysis brings about rapid formation of the sulfide by a radical-chain process. Yields of isolated product seldom fall below 75%, Eq. (28). This ap-... 

SCHEME 5.25 Preparation of diaryl sulfides from aryl benzyl sulfides. 

Several palladium catalysts for formation of aryl sulfides from aryl halides have been investigated more recently. A combination of Pd2(dba)3 and DPEphos catalyzed the formation of a broad range of diaryl sulfides in the presence of 1 mol.% palladium and NaO-t-Bu base in toluene solvent.12,rThe highest yields of alkyl aryl sulfides were obtained from aryl triflates and n-butyl thiol catalyzed by a combination of palladium acetate and BINAP. However, these reactions contained 10 mol.% catalyst, were long, and required deactivated aryl triflates. A combination of Pd2(dba)3 and DPPF catalyzed the coupling of thiols with resin-bound aryl halides.121... 

The final products of oxidation of diarylselenides and tellurides (and sulfides as well) in the presence of nucleophiles are the corresponding chalcogen (IV) compounds. In the presence of water, the selenoxide or telluroxide (or the corresponding dihydroxy selenane or tellurane) is the final product. This still leaves several possible pathways, leveraged from early mechanistic studies done using electrochemical techniques on diaryl sulfides and outlined by Engman (Fig. 32). In these pathways, the initial radical cation can react with a nucleophile present in solution, or the dication resulting from further oxidation or disproportionation can do so. 

At the time of the earlier review (66HC1155), it was already known that combinations of arenes with sulfur, or with sulfur mono- or dichlorides in the presence of Lewis acids (IV,B,1), or of aryl thiols, diaryl sulfides, or disulfides (IV,B,2 and 3) again heated with Lewis acid catalysts, generate thianthrenes, sometimes in acceptable preparative yields. A complimentary method is the treatment of aryl thiols with c. H2SO4. Routes from arenes and aryl thiols almost certainly involve the initial formation of diaryl sulfides. All these methods inevitably give symmetrical thianthrenes carrying identical substituents on each benzene ring (Scheme 9), unless the second sulfur is introduced in a controlled fashion into a preformed, unsymmetrical diphenyl sulfide. 

Di-/erJ-butylthianthrene and 1,3,6,8-tetra-tert-butylthianthrene were obtained from the diaryl sulfides in moderate yields by reaction with c. H2SO4 in nitromethane (68CB2956). A modified diaryl disulfide approach was based on intramoleculeir free radical substitution an o-phenoxy- (95% yield) or o-phenylthio-substituent (40% yield) being displaced as a radical (75G841). 

Naphthothiophenes were obtained in much better yields by photocyclization of naphthyl vinyl sulfides (78JA2140), as were substituted dibenzothiophenes from diaryl sulfides (75S532). 

Alkyl- or aryl-dibenzothiophenes are conveniently prepared from the 2-arylthio-cyclohexanones, which are readily cyclized and dehydrogenated to yield the respective 1-, 2-, 3- or 4-substituted dibenzothiophenes (382 equation 9 Section 3.15.2.3.2). More complex polycyclic systems are available, using suitable aryenethiols, such as naph-thalenethiols, and 2-bromo-l-tetralone to synthesize the appropriate 2-arylthio ketones. Diaryl sulfides can be converted to dibenzothiophene derivatives in satisfactory yields by photolysis in the presence of iodine (equation 10) (75S532). Several alkyldibenzothiophenes with substituents in the 2- and/or 3-positions were prepared in satisfactory yield by the condensation of dichloromethyl methyl ether with substituted allylbenzo[6]thiophenes (equation 11) (74JCS(P1)1744). 

Unsymmetrical diaryl sulfides (60 R = 2-NO2, 4-NO2, 2,4-(N02)2 R = H, 4-NMe2) were obtained in 80-97% yields from the reaction under PTC conditions of nitro-activated aryl halides with arenethiolates generated in situ from the reduction of the corresponding diaryl disulfides with aminoiminomethanesul-finic acid (61).192 Arylthiolates carrying electron-withdrawing substituents were not sufficiently reactive. The reaction could also be applied to the synthesis of diaryl selenides, but not of ditellurides. 

Symmetrical diaryl sulfides were produced in fair yield from the PTC reaction of sodium sulfide with molten aryl chlorides activated by a cyano, nitro, phthalimido or anhydrido group.193 Typical conditions require use of a 3 1 mole ratio of aryl chloride to Na2S and 10% of catalyst (crown ethers and onium salts) at 200 C for 24 h. 

The photostimulated reaction between aryl halides and arenethiolates gives diaryl sulfides (equation 47) and examples are given in Table 6. The yields obtained from substituted iodobenzenes are generally high but reactions with heteroaryl halides are less prominent and, for example, normally reactive 2-chlo-... 

Methyl thiosalicylate provides both electrophilic and nucleophilic sites for annulation of arynes generated from silylaryl triflates in the presence of CsF. An initial intermolecular nucleophilic coupling to afford a diaryl sulfide 529 is followed by an intramolecular electrophilic cyclization and thioxanthones result. The use of THF as solvent suppresses the competitive proton abstraction which leads to methyl 2-thiophenoxybenzoate (Scheme 211) <2005OL4273>. 

N03)j, a newcomer to the arena of oxidants, is useful for the acetoxylation of aromatic side chains in benzylic positions [415, 416] and for the oxidation of methylene or methyl groups that are adjacent to aromatic rings to carbonyl groups [238, 415, 417]. The reagent also oxidizes alcohols to aldehydes [418, 419, 420, 421] and phenols to quinones [422, 423], cleaves vicinal diols to ketones and a-hydroxy ketones to acids [424, 425], and converts diaryl sulfides into sulfoxides [426]. A specialty of ammonium cerium nitrate is the oxidative recovery of carbonyl compounds from their oximes and semicarbazones [422, 427] and of carboxylic acids from their hydrazides [428] under mild conditions. 

Previously, Andersen et al. had attempted to prepare sulfuranes from the reactions of diaryl sulfoxides with aryl Grignard reagents and aryl lithium agents. They reported that the reactions give initially the corresponding triaryl sulfoni-um salts, from which two pathways, namely the formation of tetraaryl sulfuranes and the formation of benzyne, take place simultaneously, on the basis that they obtained diaryl sulfides and biaryls derived from benzyne, as shown in Scheme 7 [37]. 

Diaryl sulfides. The phosphazene base P2—Et (1) is useful in the CuBr-promoted reaction between ArSH and ArT in toluene. Bases of this class are very strong and hindered, they generate highly nucleophilic naked anions from various acids (including carbon acids). 

Under these conditions diaryl sulfides can be obtained from the sulfoxides in 85-90% yield. ... 

A high yield synthesis of diaryl ethers involves nucleophilic attack by phenoxide on arynes generated from iodobenzenes. The arynic nature was established with substituted iodobenzenes ( -MePhI and phenol, for example, gave 35% m-tolyl phenyl ether as well as 25% of t -tolyl phenyl ether). Diaryl sulfides were similarly prepared from thiophenols and iodoarenes. 

The partial oxidation of sulfides to sulfoxides has been accomplished in a few cases by careful control of the reaction stoichiometry and conditions. A biphasic procedure for sulfoxide formation from diaryl sulfides is shown in eq 23. However, a more attractive and versatile procedure uses a solid Oxone-wet alumina reagent with a solution of the sulfide. This method permits control of the reaction to form either the sulfoxide or the sulfone simply by adjusting the amount of oxidant and the reaction temperature, as illustrated in eq 24. These oxidations are compatible with other functionality. 

Leadbeater presented a direct and rapid preparation of diaryl sulfides 75 from aryl iodides 73 using potassium thiocyanate 74 as the source of sulfur. The catalytic... 

The first successful Ar-heteroatom bond formation reaction was demonstrated in 1978 by the Japanese chemists Kosugi and Migita for a C—S bond [4]. Diaryl sulfides and arylalkyl sulfides were obtained from thiols and ArX derivatives in moderate to good yields (Scheme 3.1). 

In 2011, Park etal. [52] showed that aryl sulfides could be obtained from the coupling reaction of 5-aryl or 5-alkyl thioacetates and aryl bromides using Pd(dba)2 and dppf 5-phenyl thioacetate was the first thioacetate to be investigated, but others were also investigated (Figure 2.10). Symmetrical and unsymmetrical diaryl sulfides could also be prepared using potassium thioacetate in a one-pot... 

---