Cation Radical Perchlorate Research Articles

Reaction of Azodioxide with Thianthrene Cation Radical

We recently reported on the thianthrene cation radical perchlorate (Th·ClO4) induced oxidative decomposition of carbonates (eq 1), carbamates (eq 2), azodicarboxylate (eq 3), dicarbonate (eq 4), peroxides (eq 5), and disulfide (eq 6) where R in equations is tert-butyl. In each of these reactions, electron-transfer-mediated C,N, C,O or C,S bond cleavage was found. Substantial bond weakening was shown to accompany the tert-butyl cation due to the electron loss from these substrates. In a continuation of our work on N,N'-dioxoazobis(2methyl-2-propane) (1) in acetonitrile solution at room temperature, C,N and N,O cleavages, followed by addition of Th·ClO4 to azodioxide, 1, was found to give thianthrene oxide (ThO) and N-t-butylacetamide (3), with evolution of nitrogen gas. Reactions of Th·ClO4 with anions, such as nitrite and nitrate ions, have been reported, but its reactions with molecules with an abnormal number of bonds have not been documented. This work affords the first example of the addition of a cation radical to formal negatively charged oxygen within a neutral molecule. Reactions of nitrite and nitrate ions with Th·ClO4 were found to give thianthrene 5-oxide (ThO) quantitatively (Scheme 1). Reactions with O-labeled nitrite and nitrate ions showed that the oxygen in ThO came from the nitrite and nitrate ions respectively. In the present study, as with the other oxidative decomposition, the major products from the reaction of 1 with Th·ClO4 are also characteristic of tert-butyl cations, which imply carbocationic chemistry is predominantly observed from a nitrosoalkane dimer. The products obtained were N-tbutylacetamide (3), ThO and N2 as determined by quantitative GC and GC/MS analyses. N-t-butylacetamide (3) from the tert-butyl cation, which was isolated in a yield of 91%, and ThO (76%) was obtained by oxygen transfer from 1. Without doubt, 3 arose from hydration, during workup, of a Ritter-type intermediate (Me3CN=CMe) from the reaction of Me3C with the MeCN solvent. Accordingly, all reactions were carried out with a 2:1 stoichiometry of the cation radical and 1. Generally, in the reaction of thianthrene cation radical perchlorate, ThO is obtained as a side product from the hydrolysis of Th·ClO4 by water, either adventitiously in the solvent or added during workup. However, in this

Reactions of Two Isomeric Thiols with Thianthrene Cation Radical

Thianthrene cation radical perchlorate () reacted readily with two isomeric thiols, benzylthiol (1) and 4-methylbenzenethiol (7) in an acetonitrile solution at room temperature. From the reaction of 1, the major products, N-benzylacetamide (4) and benzyl sulfide (5), are characteristic of benzyl carbocations while the minor one, benzyl disulfide (6) implies free radical component of the reaction. It is unprecedented that the formation of a benzyl carbocation was caused by the extrusion of sulfur atoms from benzyl sulfur cations (3). In contrast, from the reaction of 7, only p-tolyl disulfide (10) was obtained from both sulfur radicals and cations. In the reaction of 7 the thio-extrusion was not observed from the p-tolyl sulfur cation (9). A thianthrene cation radical () was reduced quantitatively to thianthrene (Th) in both reactions.

Synthesis, Conformation, and Complexation of Novel 25,26,27,28- Tetrahydroxy-5,11:17,23-bis[[2,2‘-thioxydi(o-phenylene)dithioxy]- diphenylthio]calix[4]arene

Calix[4]arenes 1a,b having an electron-donating group, i.e., OH and OMe, at the lower rim reacted with thianthrene cation radical perchlorate in CH3CN at room temperature to give the corresponding thianthrenium perchlorates 3a,b in excellent yields. Treatment of 3a,b comprising a mixture of conformational isomers with NaSH.xH2O in DMF at reflux afforded the sulfur-containing cyclized compounds 4a,b, respectively. Compound 4a having a cone conformation consisted of two conformational isomers in a ratio of 0.077:1. Temperature-dependent 1H NMR study in DMF showed that conformational isomerization between the two isomers occurred with energy barriers of 14.97 and 14.10 kcal/mol at 100 and 110 degrees C, respectively. The Jobs plot of 4a against Ag+ picrate indicated that compound 4a strongly produced a 1:2 complex with Ag+ ions. Molecular mechanics calculations indicated that the conformation of the energy-minimized 4a-2Ag+ picrate complex had two crushed pyramidal geometries made up of Ag+ ion and four sulfur atoms, i.e., S1, S2, S4, S5 and S6, S7, S9, S10, respectively.

Decomposition of Alkene Adducts of Thianthrene Cation Radical in Nitrile Solvents. Formation of Alkyl-2-oxazolines and a New Class of Four-Component Products: 5-[(1-Alkoxyalkylidene)ammonio]alkylthianthrenium Diperchlorates

The monoadducts (4a-d) of thianthrene cation radical perchlorate (1a) and isobutene, 2-methylbutene, 2-methyl-2-butene, and 2-methylpentene decompose spontaneously in acetonitrile (MeCN) solution, with the formation of thianthrene (Th). Decomposition of 4a (1,2-(5,10-thianthreniumdiyl)-2-methylpropane diperchlorate) and 4a', the corresponding dihexafluorophosphate, was studied in depth and extensively with (1)H and (13)C NMR spectroscopy. Decomposition of 4a was found to involve the solvent itself as well as water in the solvent, remaining from incomplete drying, and gave, apart from Th, successively, the perchlorate salts of 2,4,4-trimethyl-2-oxazoline (6) and 2-amino-2-methylpropyl acetate (7). These salts, 6-HClO(4) and 7-HClO(4), respectively, were prepared and used in understanding the reactions of 4a as well as the relationships among 6, 7, and 2-(acetylamino)-2-methyl propanol (8) in acidified MeCN solution. Decompositions of 4a-d in MeCN and other nitriles (RCN) containing an added alcohol (R'OH) led to new products, 5-[(1-alkoxyalkylidene)ammonio]alkylthianthrenium diperchlorates (5a-u). These compounds were identified with (1)H and (13)C NMR spectroscopy and, in part, with X-ray crystallography and elemental analysis. The mechanisms of formation of 5-7 are discussed.

Adducts of phenoxathiin and thianthrene cation radicals with alkenes and cycloalkenes.

Phenoxathiin cation radical perchlorate (PO.+ClO4(-)) added stereospecifically to cyclopentene, cyclohexene, cycloheptene, and 1,5-cyclooctadiene to give 1,2-bis(5-phenoxathiiniumyl)cycloalkane diperchlorates (4-7) in good yield. The diaxial configuration of the PO+ groups was confirmed with X-ray crystallography. Unlike additions of thianthrene cation radical perchlorate (Th.+ClO4(-)) to these cycloalkenes, no evidence for formation of monoadducts was found in the reactions of PO.+ClO4(-). This difference is discussed. Addition of Th.+ClO4(-) to five trans alkenes (2-butene, 2-pentene, 4-methyl-2-pentene, 3-octene, 5-decene) and four cis alkenes (2-pentene, 2-hexene, 2-heptene, 5-decene) gave in each case a mixture of mono- and bisadducts in which the configuration of the alkene was retained. Thus, cis alkenes gave erythro monoadducts and threo bisadducts, whereas trans alkenes gave threo monoadducts and erythro bisadducts. In these additions to alkenes, cis alkenes gave predominantly bisadducts, while trans alkenes (except for trans-2-butene) gave predominantly monoadducts. This difference is explained. 1,2-Bis(5-phenoxathiiniumyl)cycloalkanes (4-7) and 1,2-bis(5-thianthreniumyl)cycloalkanes underwent fast elimination reactions on activated alumina forming, respectively, 1-(5-phenoxathiiniumyl)cycloalkenes (8-11) and 1-(5-thianthreniumyl)cycloalkenes (12-16). Among adducts of Th.+ClO4(-) and alkenes, monoadducts underwent fast ring opening on alumina to give (5-thianthreniumyl)alkenes, while bisadducts underwent fast eliminations of H+ and thianthrene (Th) to give (5-thianthreniumyl)alkenes also. Ring opening of monoadducts was a stereospecific reaction in which the configuration of the original alkene was retained. Thus, erythro monoadducts (from cis alkenes) gave (E)-(5-thianthreniumyl)alkenes and threo monoadducts (from trans alkenes) gave (Z)-(5-thianthreniumyl)alkenes. Among bisadducts, elimination of a proton and Th occurred and was more complex, giving both (E)- and (Z)-(5-thianthreniumyl)alkenes. These results are explained. Configurations of adducts and (5-thianthreniumyl)alkenes were deduced with the aid of X-ray crystallography and (1)H and (13)C NMR spectroscopy. In the NMR spectra of (E)- and (Z)-(5-thianthreniumyl)alkenes, the alkenyl proton of Z isomers always appeared at a lower field (0.8-1.0 ppm) than that of E isomers.

Synthesis of 2‐(2‐, 3‐, and 4‐pyridyl)benzoxazoles by the reaction of phenolic schiff bases with thianthrene cation radical

Abstract2‐(2‐, 3‐, and 4‐Pyridyl)benzoxazole derivatives were prepared in excellent yields by the oxidative cyclization of phenolic Schiff bases with thianthrene cation radical perchlorate in the presence of 2,6‐di‐tert‐butyl‐4‐methylpyridine.

New Mechanism for the Reaction of Thianthrene Cation Radical Perchlorate with tert-Butyl Peroxide

A new reaction mechanism is proposed for the reaction of thianthrene cation radical perchlorate <TEX>$(Th^{+{\cdot}}CIO_4^-}$</TEX> and tert-butyl peroxide in acetonitrile at room temperature on the basis of experimental and theoretical results. Rapid C-O bond rupture instead of O-O bond cleavage was observed by a good peroxy radical trapping agent, thianthrene cation radical. Products were N-tert-butyl acetamide, thianthrene 5-oxide (ThO), thianthrene 5,5-dioxide <TEX>$(SSO_2)$</TEX>, and thianthrene (Th). Thianthrene 5,10-dioxide (SOSO) was not obtained. A comparative computational study of the cation radical of tert-butyl peroxide is made by using B3LYP and CBS-4. The computational results are helpful to explain the reaction mechanism.

Addition of Thianthrene Cation Radical to Cycloalkenes. An Unexpected Monoadduct.

Whereas the addition of thianthrene cation radical perchlorate (Th•+ClO4-) to cyclohexene gives a bisadduct, namely, trans-1,2-bis(5-thianthreniumyl)cyclohexane diperchlorate (1), and additon to other alkenes and alkynes also gives trans-bisadducts, addition to cyclooctene gave only a cis-monoadduct, namely, 1,2-(5,10-thianthreniumdiyl)cyclooctane diperchlorate (2a). Similar monoadducts 2b−d were obtained from the addition of Th•+BF4-, Th•+SbF6-, and Th•+PF6- to cyclooctene. The structure of the monoadduct was deduced from its 1H and 13C NMR spectra, from the stoichiometry of its formation, and from the stoichiometry of its reaction with NaSPh, which gave equimolar amounts of cyclooctene, thianthrene, and diphenyl disulfide. The structure was confirmed with X-ray crystallography. Addition of Th•+ salts to cyclopentene and cycloheptene gave mixtures of mono- and bisadducts. The bisadduct of Th•+SbF6- to cyclopentene, separated from the small amount of monoadduct by crystallization, was shown with X-ray cry...

Reactions of 5-(alkyl)thianthrenium and other sulfonium salts with nucleophiles

A series of 5-(alkyl)thianthrenium triflates (3a–d, g–i) with alkyl (R) groups Me (a), Et (b), isoPr (c), 2-Bu (d), cyclopentyl (g), cyclohexyl (h) and cycloheptyl (i) were prepared by alkylation of thianthrene (Th) with alkyl formate and trifluoromethanesulfonic (triflic) acid. Benzylation (3f) was achieved with benzyl bromide and silver triflate. 5-(Neopentyl)thianthrenium perchlorate (3e) was prepared by reaction of thianthrene cation radical perchlorate with dineopentyl mercury. Methyl- (4a) and cyclohexyldiphenylsulfonium triflate (4b) were made by alkylation of diphenyl sulfide. Benzyldimethyl- (5a), dibenzylmethyl- (5b) and benzylmethylphenylsulfonium perchlorate (5c) were prepared in standard ways. Reactions of these sulfonium salts with iodide ion and thiophenoxide ion were studied for comparison with our earlier reported reactions of comparable 5-(alkoxy)thianthrenium and methoxydiphenylsulfonium salts. It is deduced that reactions of 3–5 with nucleophiles (Nu−) I− and PhS− follow traditional SN2 and E2C paths. Thus, the salts 3a–c, e and f gave virtually quantitative yields of RNu and Th, while small amounts of butene(s) were obtained from 3d. The cycloalkyl salts 3g–i gave amounts of cycloalkylNu and cycloalkene typical of competition of SN2 and E2C routes in the classical reactions of cycloalkyl halides and tosylates with I− and PhS− ions. Whereas 4a gave only SN2 products, 4b gave SN2 and E2C products typical of SN2/E2C competition. Among the salts 5a–c displacement of the benzyl group was dominant (5a) or exclusive (5b, c), thus exhibiting the preferential displacement of a benzyl group that has been fully documented in earlier studies of SN2 reactions. Qualitative comparison showed that 3a (methyl) reacted much faster than 3e (neopentyl) with PhS−. Unlike alkoxysulfonium salts, the salts 3–5 do not appear to undergo reactions at the sulfonium sulfur atom. Copyright © 2000 John Wiley & Sons, Ltd.

ChemInform Abstract: s‐Triazolo[3,4‐a]phthalazines from 1‐Phthalazinylhydrazones by Thianthrene Cation Radical Perchlorate.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

S-Triazolo[3,4-α]Phthalazines From 1-Phthalazinylhydrazones by Thianthrene Cation Radical Perchlorate

1-Phthalazinylhydrazones 4 gave i,-triazolo[3,4-a]phthalazines 5 in 94-98% yields by thianthrene cation radical perchlorate (Th+′C104 -).

Primary and secondary 5-(alkyloxy)thianthrenium perchlorates. Characterization with1H NMR spectroscopy, reactions with iodide and bromide ion, and thermal decomposition in solution

A series of 5-(alkyloxy)thianthrenium perchlorates has been made in which the alkyl group is primary (1a-1p) and secondary (2a-2g). Preparations were carried out by reaction of the corresponding alkanol with thianthrene cation radical perchlorate in CH2Cl2solution followed by precipitation of the perchlorate salt with dry ether.1H NMR spectroscopy reveals that the presence of a stereogenic center in the alkyl group causes inequivalence in the ordinarily paired protons (e.g., H-4, H-6) of the thianthrenium ring. Reaction of iodide and bromide ion with primary alkyl-group compounds (e.g., methyl, ethyl, propyl, butyl) gave the alkyl halide in very good yield and by a second-order kinetic displacement. The second product was thianthrene 5-oxide (ThO). Rate constants for some of these reactions are reported. Reaction of secondary alkyl group compounds (e.g., 2-propyl, 2-pentyl, 2-hexyl, and 3-hexyl) with iodide ion gave good yields of alkyl iodide but also increasing evidence for a side reaction at the sulfonium sulfur, leading to I2, thianthrene, and secondary alkanol. Decomposition of some compounds at 100°C in solution (acetonitrile or 1,2-dichloroethane) was studied and gave alkene(s) and ThO.Key words: thianthrene cation radical, 5-(alkyloxy)thianthrenium perchlorates.

ChemInform Abstract: Cation Radicals with 2‐Pyridylhydrazones in Nitrile Solvents. s‐Triazolo[4,3‐a]pyridines by Thianthrene Cation Radical Perchlorate and 1‐(2‐Pyridyl)‐1,2,4‐triazoles by Tris(2,4‐dibromophenyl)aminium Hexachloroantimonate.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Structure and Thermal Decomposition of Some 5-(Cyclohexyloxy)thianthreniumyl Perchlorates

Five sets of cis- and trans-substituted cyclohexanols were used for reaction with thianthrene cation radical perchlorate, namely, cis- and trans-cyclohexane-1,2-diol, cis- and trans-2-methyl-, 3-methyl-, and 4-methylcyclohexanol, and cis,cis- and trans,trans-3,5-dimethylcyclohexanol. Reaction in CH2Cl2 solution and precipitation with ether gave the corresponding crystalline 5-(cyclohexyloxy)thianthreniumyl perchlorate salts. The configuration of each salt in CDCl3 was shown by 1H and 13C NMR spectroscopy to correspond with the configuration of the cyclohexanol from which it was made. X-ray Ortep diagrams of four of the salts confirmed the structure deduced from NMR spectroscopy. In the NMR, inequivalence of the 1H and 13C signals from the thianthreniumyl 4- and 6-, 1- and 9-, 2- and 8-, and 3- and 7-positions was found when the 1‘-position of the cyclohexyl ring was stereogenic. In the four Ortep diagrams, the orientation of the S−O bond was psuedoaxial. Thermal decomposition of the salts made from the mo...

2-Arylbenzoxazoles from phenolic schiff's bases by thianthrene cation radical

2-Arylbenzoxazoles 2 have been made in 91–97% yields from phenolic Schiff's bases 1 by thianthrene cation radical perchlorate (Th +.ClO 4 −) in the presence of 2,6-di- tert-butyl-4-methylpyridine.

Reaction of thianthrene cation radical with alcohols: Isolation and chemistry of 5-cyclohexyloxythianthreniumyl perchlorate

5-Cyclohexyloxythianthreniumyl perchlorate ( 1) was prepared by reaction of thianthrene cation radical perchlorate (Th •+ClO 4 −) with cyclohexanol in CH 2Cl 2. Cyclohexene and thianthrene 5-oxide (ThO) are formed when 1 is heated in solution. Reaction of 1 with H 2 O OH − occurs at the 5-position and gives cyclohexanol and ThO. The chemistry of isolated 1 clarifies earlier work on the reaction of Th •+ClO 4 − with cyclohexanol.

Reactions of Thianthrene Cation Radical with Acyclic and Cyclic Alcohols

Thianthrene cation radical perchlorate (Th .+ ClO 4 - ) reacted readily with cycloalkanols (C 5 , C 7 , C 8 , and C 12 ), alkan-2-ols (C 3 , C 6 , C 6 , and C 8 ), 3-hexanol, neopentyl alcohol, a number of benzyl alcohols, dl- and (S)-1-phenylethanol, cyclopentyl- and cyclohexylmethanols, the exo- and endo-borneols, and norborneols. Reactions were carried out with an excess of the alcohol in acetonitrile solution containing 2,6-di-tert-butyl-4-methylpyridine. Products were alkenes, ethers, and N-substituted acetamides, depending on the structure of the alcohol. Thianthrene (Th) and its 5-oxide (ThO) were formed in equal amounts. The sum of amounts of products from the alcohol was equal t the amount of ThO. All reactions are interpretable on the basis of the ultimate formation and further reactions of a 5-alkoxythianthreniumyl ion (ROTh + ). The predominant formation of nortricyclene from the norborneols is striking and is discussed. Swern-Moffatt-type oxidations of the alcohols were not observed

Reaction of Thianthrene Cation Radical with Diarylmercurials. Search for Single Electron Transfer Is Elusive

Diarylmercurials (Ar2Hg) with Ar = p-tolyl Ib, o-tolyl Ic, p-anisyl Id and 2-allyloxy-4,5-dimethylphenyl Ie, reacted with thianthrene cation radical perchlorate (Th.+ClO4-) in two stoichiometric ratios: 2 : 1 and 4 : 1 (Th.+ClO4-/Ar2Hg). In the 2 : 1 ratio the products were the 5-arylthianthreniumyl perchlorates IIb - IIe, thianthrene (Th) and ArHg+ClO4- (assayed as ArHgCl, III) in quantitative yields. In the 4 : 1 ratio reaction with ArHg+ occurred, too, and the products were IIb - IIe, Th, the complex Th3Hg(ClO4)2 and HgO (after workup). In contrast, Ph2Hg (Ia) did not react beyond the 2 : 1 stoichiometry. In the reactions with Ie, no evidence for formation and cyclization of free 2-allyloxy-4,5-dimethylphenyl radical was found. Reaction of and product formation from these arylmercurials, therefore, does not occur in single electron transfer steps that lead to free aryl radicals. Instead electron transfer appears to occur within a complex of Ar2Hg with Th.+ from which II and other products are subsequently formed.

Reaction of thianthrene cation radical with alcohols: Cyclohexanols

Cyclohexanol ( 1), 4-methylcyclohexanol ( 2), 4- tert -butylcyclohexanol ( 3), cis -2-methyl- ( 4) and trans -2-methylcyclohexanol ( 5) reacted cleanly with thianthrene cation radical perchlorate (Th .+ClO 4 −) in the presence of 2,6-di- tert -butyl-4-methylpyridine (DTBMP). The alcohols were converted quantitatively into cyclohexenes, while Th .+ was converted quantitatively into thianthrene (Th) and thianthrene 5-oxide (ThO). The oxygen atom of ThO came from the alcohol, as was demonstrated with the use of [ 18O]cyclohexanol.

Reactions of phenols with thianthrene cation radical

The phenols 2-R 1 -6-R 2 -phenol 1a-g in which R 1 =R 2 =tert-butyl, methyl, isopropyl, Cl, Br, F, and H reacted with thianthrene cation radical perchlorate (Th .+ ClO 4 - ) to give 5-(4-hydroxyaryl)thianthreniumyl perchlorates 2a-g in good yield. o-Allylphenol (1i) behaved similarly. o-tert-Butylphenol (1h) gave both 5-(3-tert-butyl-4- hydroxyphenyl)thianthreniumyl perchlorate (2h) and a quinonoidal perchlorate (3), namely, 5-(3- thianthreniumyl-5-tert-butyl-6-oxo-2,4-cyclohexadien-1-ylidene)-5,5- dihydrothianthrene perchlorate