Thallium acetate-iodine

Thallium acetate reacts with iodine and an alkene to give the trans-io do acetate derivatives in 90% yield (28) ... 

DIHYDROXYLATION Osmium tetroxide-Dihydroquinine acetate. Osmium tetrox-ide-Diphenyl selenoxide. Osmium tetroxide-Trimethylamine N-oxide-Pyiidine. Thallium(l) acetate-iodine. Triphenylmethylphosphonium permanganate. 

Pans-2-Iodocyclohexyl acetate can be isolated in essentially quantitative yield from the reaction of thallium(I) acetate, iodine, and cyclohexene in a 1 1 1 molar ratio in refluxing chloroform. lodo acetates from a representative series of alkenes including cyclohexene have been similarly prepared in 80-98% yield in glacial acetic acid which was not dried as described in this procedure. The corresponding iodo benzoates are obtained in comparable yields from reaction with thallium(I) benzoate and iodine in benzene. The deactivated olefin methyl cinnamate did not react under these conditions, and o-allylphenol underwent ring iodination to... 

Tetramethylthiourca, 359 meso-Tetraphenylporphin, 267 Tetraselenofulvalene, 200 Tetrathiafulvalenes, 387 Thallium(lll) acetate, 360-361 Thallium(l) acetate-iodine, 359-360 Thalliiim(l) bromide, 361 ThalUum(I) ethoxide, 362 Thallium(lll) nitrate, 362-365 Thallium(Ill) perchlorate, 365 Thallium(IIl) trifluoroacetate, 365 Thiepins, 5... 

Stereoselective cis-dihydroxylation of the more hindered side of cycloalkenes is achieved with silver(I) or copper(II) acetates and iodine in wet acetic acid (Woodward gly-colization J.B. Siddall, 1966 L. Mangoni, 1973 R. Criegee, 1979) or with thallium(III) acetate via organothallium intermediates (E. Glotter, 1976). In these reactions the intermediate dioxolenium cation is supposed to be opened hydrolytically, not by Sn2 reaction. 

The reaction is a sensitive one, but is subject to a number of interferences. The solution must be free from large amounts of lead, thallium (I), copper, tin, arsenic, antimony, gold, silver, platinum, and palladium, and from elements in sufficient quantity to colour the solution, e.g. nickel. Metals giving insoluble iodides must be absent, or present in amounts not yielding a precipitate. Substances which liberate iodine from potassium iodide interfere, for example iron(III) the latter should be reduced with sulphurous acid and the excess of gas boiled off, or by a 30 per cent solution of hypophosphorous acid. Chloride ion reduces the intensity of the bismuth colour. Separation of bismuth from copper can be effected by extraction of the bismuth as dithizonate by treatment in ammoniacal potassium cyanide solution with a 0.1 per cent solution of dithizone in chloroform if lead is present, shaking of the chloroform solution of lead and bismuth dithizonates with a buffer solution of pH 3.4 results in the lead alone passing into the aqueous phase. The bismuth complex is soluble in a pentan-l-ol-ethyl acetate mixture, and this fact can be utilised for the determination in the presence of coloured ions, such as nickel, cobalt, chromium, and uranium. 

SO2CI2) or with I2 and silver acetate. Enol acetates have been regioselec-tively iodinated with I2 and either thallium(I) acetateor copper(II) acetate. ot,P-... 

A. trans-l,2-Cyclohexanediol. In a 100-ml., round-bottomed flask equipped with a reflux condenser protected with a drying tube are placed a magnetic stirring bar, 17.56 g. (0.0667 mole) of thallium (I) acetate (Note 1), and 40 ml. of dried acetic acid (Note 2). The mixture is stirred and heated at reflux for 1 hour. To the cooled mixture are added 2.84 g. (3.5 ml., 0.0346 mole) of cyclohexene (Note 3) and 8.46 g. (0.0333 mole) of iodine (Note 4). The resulting suspension is stirred and heated at reflux for 9 hours (Note 5), and then cooled to room temperature. The yellow precipitate of thallium(I) iodide is filtered and washed thoroughly with ethyl ether. The filtrates are comhined, the solvents are removed under reduced pressure with a rotary evaporator (Note 6), and the residual liquid is dissolved in dry ethyl ether. The turbid solution is dried with anhydrous potassium carbonate, and the solvent is again removed by rotary evaporation (Note 6), affording 5.4-6.3 g. of trans-1,2-cyclohexanediol diacetate as a mobile, brown liquid (Note 7). 

The mechanisms of these reactions are presumably analogous to those of the Pr6vost and Woodward-Prevost reactions. In the first step of the reaction of iodine and thallium(I) acetate with cyclohexene in both parts A and B of this procedure, trans-2-iodocyclohexyl acetate is formed. The second equivalent of thal-lium(I) acetate scavenges iodide ion during formation of the 1,3-... 

Vicinal iodo carboxylates may also be prepared from the reaction of olefins either with iodine and potassium iodate in acetic acid/ or with N-iodosuccinimide and a carboxylic acid in chloroform. " A number of new procedures for effecting the hydroxylation or acyloxylation of olefins in a manner similar to the Prevost or Woodward-Prevost reactions include the following iodo acetoxylation with iodine and potassium chlorate in acetic acid followed by acetolysis with potassium acetate reaction with iV-bromoacetamide and silver acetate in acetic acid reaction with thallium(III) acetate in acetic acid and reaction with iodine tris(trifluoroacetate) in pentane. ... 

STEREOSELECTIVE HYDROXYLATION WITH THALLIUM(I) ACETATE AND IODINE trans- AND cis-l,2-CYCLOHEXANEDIOLS... 

Significant amounts of the bicyclo[3.3.1]nonane adduct and of the octahydropental-enes were isolated also from the reaction of 3 with preformed iodine acetate and iodine acetate thallium (equation 75)94 whereas only the monocyclic 1,2-adducts were obtained from treatment of 3 with iodine azide, iodine isocyanate or iodine nitrate95. The different propensity to give transannular products with these latter reagents has been related to the different positive charge density on carbons in the corresponding iodonium ion intermediates. 

Lithiation and mercuration are directed by the oxygen atom and occur at the 4-position, but thallation, achieved by treatment of dibenzofuran with thallium(III) isobutyrate at 110°C, affords the 2-thallium di(isobutyrate), which may be converted to the 2-iodo compound by reaction with iodine. Mercuration is achieved by treatment of dibenzofuran with mercuryfll) acetate at 150°C, and the resultant 4-mercuric acetate (56%) may also be converted to the iodo compound. ... 

The iodo acetal could be easily obtained (as a mixture of E and Z isomers, 40/60), by a nickel catalyzed iodine-bromine exchange. This synthon reacted smoothly with the C15 tertiary allylic alcohol in the presence of a catalytic amount of palladium acetate and a stoechiometric amount of either a silver or a thallium salt. The C20 hydroxy-acetal was obtained in 38% yield, as a mixture of E and Z isomers (48/52). Finally retinal was obtained by treatment with dilute HBr in refluxing acetone, as a mixture of E and Z isomers (C(9)=C(io) and C(i3)=C(i4)), Fig. (32). 

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