Bis phenyliodonium

Bicyclic enediynes were obtained from the Diels-Alder adducts of cyclopenta-diene or furan with bis phenyliodonium acetylene triflate and lithium alkynyl cuprates. In this case the reaction conditions were more demanding and yields less satisfactory. 

Sodium thiophenoxide and bis phenyliodonium acetylene triflate afforded cleanly l,2-bis(phenylthio)acetylene [6]. Alkynyl iodonium salts have alkynylated several arene sulphonates which were converted into alkynyl aryl sulphones. The process is probably the best among other methods, as far as yield, availability of starting materials, non-toxicity and ease of handling are concerned. 

The treatment of bis(phenyliodonium)diyne triflates, 19 (n = 5,6,8), with sodium p-toluenesulfinate provides access to disulfones possessing spiroannulated or tethered cyclopentene rings (equation 57)86. However, because migration of the / -toluenesulfonyl group in the intermediate carbenes is competitive with insertion, the yields of the bis-cyclopentene compounds are relatively low, and disulfones of general structures 20 and 21 are also obtained. 

The propensity of the thiocyanate ion for alkynylation with alkynyliodonium ions has also been demonstrated with a series of bis(phenyliodonium)diyne triflates (equations 61 and 62)43. The efficient production of diynediyl dithiocyanates in these reactions may be contrasted with the favored formation of mono- and bis-cyclopentenyl sulfones from bisiodonium diyne salts and sodium/ -toluenesulfinate (see equation 57)86. 

The treatment of [bis(phenyliodonium)]ethyne ditriflate with triphenylphosphine has also been investigated40,41. The products depend on the stoichiometric ratios of the reactants. Thus, with one equivalent of triphenylphosphine, a monoiodonium-monophos-phonium derivative of acetylene is obtained, but with two equivalents of the phosphine, [bis(triphenylphosphonium)]ethyne ditriflate is produced (equation 72). When three equivalents of triphenylphosphine are employed in acetonitrile spiked with H20 or D20, a fram -alkenediyl bisphosphonium salt is generated (equation 73)41. The reduction of the triple bond and formation of triphenylphosphine oxide in this reaction is thought to proceed at the bisphosphonium alkyne stage41. 

The MCI cyclopentene annulations proceed with moderate efficiency and have been utilized for the construction of polycyclic molecules with fused, spiro and tethered ring systems (e.g. equations 118-120)28. With bis(phenyliodonium) diyne salts, biscyclopentene annulations are observed (e.g. equation 121)86. 

Bis(phenyliodonium)]ethyne ditriflate reacts similarly with cyclopentadiene, furan and 2,5-diphenyl-3,4-benzofuran to give the corresponding bisiodonium salts (equation 144)41. 

It has already been noted that the enolates of unactivated monocarbonyl compounds do not undergo alkynylation with alkynyliodonium salts3. It is therefore particularly intriguing that [bis(phenyliodonium)]ethyne ditriflate reacts with the silyl enol ether (SEE) of acetophenone to give an allenic diketone (equation 151)41. Except for the SEE of cyclohexanone, which gives a black tar with the bisiodonium compound41, similar studies of other SEEs have not been reported. 

Diels-Alder reactions of alkynyl(phenyl)iodonium triflates (i.e. containing electron-withdrawing groups in the alkynyl moiety) and [bis(phenyliodonium)] ethyne ditrifiate have been employed for the synthesis of cyclic vinyliodonium salts (equations 143 and 144)17,41. The availability of such compounds offers considerable potential for the elaboration of densely functionalized cyclic molecules. 

Phenoxide ion, unlike alkoxides, interacts favorably with alkynyliodonium species. Reaction of two equivalents of lithium phenoxide with the [bis(phenyliodonium)ethyne, 30, results in diphenoxyacetylene, 79 [24] [Eq. (36)]. Benzofurans, 81, are obtained in the reaction of 23 with PhONa in methanol [Eq. (37)] [64]. As indicated, these products arise via insertion of the intermediate carbene, 80, into the ortho-C-H bond. 

Single-crystal X-ray structures have been reported for the following aryl- and heteroaryliodo-nium salts diphenyliodonium triiodide [412], (2-methylphenyl)(2-methoxyphenyl)iodonium chloride [413], (2-methoxy-5-methylphenyl)(4-methoxy-2-methylphenyl)iodonium trifluoroacetate [414], (2-methoxy-5-methylphenyl)(4-methoxyphenyl)iodonium trifluoroacetate [415], a complex of diphenyliodonium tetrafluoroborate with pyridine [416], a complex of diphenyliodonium tetrafluoroborate with 1,10-phenanthroline [417], a complex of diphenyliodonium tetrafluoroborate with 18-crown-6 [418], 1-naphthylphenyliodonium tetrafluoroborate [419], 3,10-dimethyl-10//-dibenzo[, e]iodinium tetrafluoroborate [420], aryl(pentafluorophenyl)iodonium tetrafluoroborates [421], 4,4 -[bis(phenyliodonium)]-diphenylmethane ditriflate [422], [bis(4-methoxyphenyl)](diethylaminocarbodithioato)iodine(in) [423], di(p-tolyl)iodonium bromide [424], diphenyliodonium chloride, bromide and iodide [425,426], diphenyliodonium nitrate [427], diphenyliodonium tetrafluoroborate [428], thienyl(phenyl)iodonium salts [401], (anft-dimethanoanthracenyl)phenyliodonium tosylate and hexafluorophosphate [429] and 3-mesityl-5-phenylisoxazol-4-yl(phenyl)iodonium p-toluenesulfonate [409]. 

Sonochemically induced cation-radical intramolecular cyclization on action of an iodo-nium salt was also demonstrated (Arizawa et al. 2001). Being oxidized with phenyliodonium bis(trifluoroacetate), l-(3-anisyl)-2-(l,3-cyclohexadien-2-yl) ethane formed the cation-radical and then 5 -methoxyspiro[cycloxehane-l,T-indan]-2,6-dione. The yield of this final product was high enough. 

Saito et al. <1995S87> described a new method for the synthesis of heterocycle-fused[c]thiophenes via reaction of aryl heteroaryl thioketones with the carbene precursors. Heteroaromatic thioketones A react with carbenoids generated from bis(arylsulfonyl)diazomethanes or phenyliodonium bis(phenylsulfonyl)methylides to give heterocycle-fused[f]thiophenes B. The reaction involves the ring closure of the intermediary thiocarbonyl ylides, followed by restorative aromatization via the elimination of a sulfenic acid (Equation 11). 

Thiophenium bis(alkoxycarbonyl)methylides (44) are obtained in high yield by rhodium(II) carboxylate-catalyzed reaction of diazomalonate esters with thiophene derivatives (88JCS(P1)1023). Likewise, ylides from benzo[b]thiophene and dibenzothiophene (e.g. 45) have also been reported by tram-ylidation using phenyliodonium bis(phenylsulfonyl)methylide (88JHC1599). 

Cation radical cyclization can be performed (and accelerated significantly) under sonication. Thus, the reaction of methyl vanillate with phenyliodonium bis(acetate) is initiated by ultrasonic irradiation and gives rise to the corresponding oquinone monoketal, which is trapped by a series of furanes. Monoadducts are formed reactions can be conducted at room temperature and are essentially complete within 15-50 min (Avalos et al. 2000). 

The only compounds of this type are some phenyliodonium salts with a carbo-ranyl group, obtained from 9-o-, 9-m- and 2-p-iodocarboranes which were converted into (dichloroiodo) and then into [bis(trifluoroacetoxy)iodo]carboranes these were coupled with benzene in presence of acid [84]. 

Phenyliodonium bis(perfluoroalkanesulfonyl)methide 200 can react with various organic substrates upon irradiation with UV light [141,142]. For example, the reaction with cyclohexene affords cycloaddition product 201, while the photolysis of 200 in benzene or toluene leads to the C-H insertion products 202 (Scheme 72) [142]. 

In contrast to (diacetoxyiodo)benzene, [bis(trifluoroacetoxy)iodo]benzene, (BTI) reacts in aqueous solvents with both terminal and non-terminal alkynes affording eventually a-hydroxyketones and 1,2-diketones, respectively. The primary reaction of terminal alkynes leads to the formation of alkynyl phenyliodonium salts, which are not isolable under the experimental conditions but have been prepared by other routes (Section 9.1.3) these are hydrolysed in situ to a-hydroxymethyl ketones, through the intermediacy of their O-tri fluoroacetates, which sometimes may be isolated as by-products. 

Whereas oxygen nucleophiles gave poor yields of alkenylated products with alkenyl iodonium salts, the reactions with sulphur nucleophiles proceeded more efficiently, leading to unsaturated sulphides and sulphones. Thus, 4-t-butylcyclohexenyl phenyliodonium salts afforded with sodium thiophenoxide 4-t-butylcyclohexenyl phenyl sulphide (81%) [3] and with sodium phenylsulphinate the corresponding sulphone (29%) in the presence of 18-crown-6, the yield of the latter rose to 80% [45]. jS-Phenylsulphonylalkenyl iodonium salts with sodium phenylsulphinate at 0°C, without any catalyst, afforded Z-l,2-bis(phenylsulphonyl)alkenes, in high yield with retention of the stereochemistry [45] ... 

Other alkynyl phenyliodonium arylsulphonates were prepared by modified procedures, notably from iodosylbenzene and alkynylsilanes, in good yields (62-89%). The decomposition stage proceeded also in satisfactory yields, up to 88% [61]. Bis alkynyl dibenzoates and ditosylates were prepared from the corresponding bis iodonium salts of the general formula PhI+C=C(CH2) C=CI + Ph, where n = 5,6,8 [62]. 

Cyano phenyliodonium triflate activated alkenes toward nucleophilic addition in wet acetonitrile 1,2-bis acetamido alkanes were obtained, whereas a diene afforded the corresponding 1,4-adducts (both isomers) (76] ... 

Alkynyliodonium triflates exhibit two distinct modes of reactivity with bis(triph-enylphosphine)ethyleneplatinum(O)113. When (terf-butylethynyl)phenyliodonium triflate is mixed with the Pt(0) complex in degassed dichloromethane, ethylene insertion occurs, and a cationic 3-propargylplatinum(II) triflate is obtained (equation 147). Employment of l-propynyl(phenyl)iodonium triflate in degassed toluene, on the other hand, leads to a square planar cr-propynylplatinum(II) complex. 

The treatment of alkenes with iodine(III) reagents usually results in functionalization of the carbon-carbon double bond. However, 1,1-diphenylethylene affords a low yield of (l,l-diphenylethenyl)phenyliodonium tosylate with HTIB (equation 181)11,138. The cyclic dithiolylidene derivative of malonic acid, shown in equation 182, undergoes decarboxylation with [bis(trifiuoroacetoxy)iodo]benzene in methanol and gives an unusual vinyliodo-nium trifluoroacetate139. Finally, when the allenylphosphonate shown in equation 183 is added to a mixture of (difluoroiodo)benzene and BF3-etherate in dichloromethane, a... 

Reaction of heteroaromatic thioketones 638 with the carbenoids, generated from phenyliodonium bis(phenylsul-fonyl)methane or bis(arylsulfonyl)diazomethanes in the presence of a copper acetylacetonate catalyst, affords heterocycle-fused [c]thiophenes 639. The reaction involves ring closure of the intermediary thiocarbonyl ylides and elimination of a sulfenic acid (Equation 33) <1995S87>. 

Reaction of chlorocarbene, generated from dichloromethyllithium, with the malono-nitrile derivative 187 affords minor amounts (2%) of the corresponding electrophilic cyclopropane (188) (equation 47). Reaction of phenyliodonium bis(methoxycarbonyl)... 

When an intimate mixture of phenyliodonium bis(arylsulfonyl)methylides (204) and excess p,p dimethylthiobenzophenone (205) containing a catalytic amount of Cu(acac)2 is briefly heated without any solvent until it melts, 2,2-di-p-tolyl-3,3-bis(phenylsulfonyl)thiirane (206) is obtained in 27% yield (Equation (31)) <89JCS(Pl)379>. With />,/> -dimethoxythiobenzophenone (207) no thiirane is formed but instead 3-/ -methoxyphenyl-6-methoxy-2-phenylsulfonylbenzo[i]thiophene (208) is obtained in 39% yield (Equation (32)). 

Similarly, 3-oxospiro[benzo[it]thiophene-2(3//)-r-cyclopropane] S,5-dioxides 3 and 4 were synthesized starting from phenyliodonium ylide 2 and alkenes with catalysis by bis(acetyl-acetonato)copper(II). The ylide is easily obtained in 95% yield from 3-oxo-2,3-dihydro-benzo[h]thiophene 1,1-dioxide and bis(trifluoroacetoxy)iodobenzene. 

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