Reagents thallium nitrate

Mercuric salts induce oxidative rearrangement of cyclic alkenes and give cycloalkane carboxaldehydes. Cyclohexene, for example, gave cyclopentane carboxaldehyde (404) in 53% yield. Acyclic alkenes such as 2-butene can also be oxidized with mercuric sulfate and sulfuric acid, giving 2-butanone in this case.566 Thallium nitrate [T1(N03)3] is an important reagent for the oxidative rearrangement of cyclic alkenes.567 The reaction is not restricted to carbocyclic compounds, but can also be applied to heterocyclic compounds as shown by the oxidation of 3,4-dihydro-277-pyran (405) to the dimethyl acetal (406) in 65% yield.568... 

Clay-supported reagent. Thallium(III) nitrate adsorbed on K-10, a mont-inorillonite clay, is a remarkably effective reagent for oxidation. Generally oxidations proceed more cleanly than with TTN in methanol. The thallium(I) nitrate formed is also bound to the support. TTN itself is a trihydrate, but (he. supported reagent appears to be nonhydrated. 

OXIDATION, REAGENTS Acetyl nitrate. Bis(tri-n-butyltin)oxide. Bromine-Hexameth-ylphosphoric triamide. f-Butyl perbenzoate. Ceric ammonium nitrate. N-chlorosuc-cinimide-Dimethyl sulfide. Chromic add. Chromic anhydride. Chromic anhydride-Acetic anhydride. Chromic anhydride-Hexamethylphosphoric triamide. 2,3-Dichloro-5,6-dicyano-l,4-benzoquinone. Dimethyl sulfoxide. Dimethyl sulfoxide-Trifluoro-acetic anhydride. Diphenylseleninlc anhydride. Iodine tris(trifluoroacetate). Lead tetraacetate. N-Methylmorpholine -N-oxide. p-NitrobenzenesulfonyI peroxide. Oxygen, singlet. Palladlumfll) chloride. Peroxybcnzimidic acid. Phenylseleninyl chloride. N-Phenyl-l,2,4-triazoline-3,5-dione. Potassium chromate. Potassium superoxide. Pyri-dinium chlorodiromate. Salcomine. Silver carbonate-Celite. Sodium hypochlorite. Sulfuryl chloridc-Silica gel. Thallium(III) acetate. ThaUium(III) nitrate. Triphenyl phosphite ozonide. Trltyl tetrafluoroborate. Uranium hexafluoride. 

ThaUous sulfate, thaUous nitrate, and thaUous and thaUic oxide are the main compounds produced in bulk quantities by Noah Chemical. Approximately 20 other thallium compounds are also available commercially from Noah Chemical, Cooper Chemical, and Alfa Products, Ventron Division, Thiokol Corporation, in research and production quantities. However, demand for thallium compounds is small and limited to such appHcations as synthetic or analytical reagents. 

The mechanism of oxidation probably involves in most cases the initial formation of a glycol (15-35) or cyclic ester,and then further oxidation as in 19-7. In line with the electrophilic attack on the alkene, triple-bonds are more resistant to oxidation than double bonds. Terminal triple-bond compounds can be cleaved to carboxylic acids (RC=CHRCOOH) with thallium(III) nitrate or with [bis(trifluoroacetoxy)iodo]pentafluorobenzene, that is, C6F5l(OCOCF3)2, among other reagents. 

Symmetrical and unsymmetrical benzoins have been rapidly oxidized to benzils in high yields using solid reagent systems, copper(II) sulfate-alumina [105] or Oxone-wet alumina [105, 106] under the influence of microwaves (Scheme 6.32). Conventionally, the oxidative transformation of a-hydroxy ketones to 1,2-diketones is accomplished by reagents such as nitric acid, Fehling s solution, thallium(III) nitrate (TTN), ytterbium(III) nitrate, ammonium chlorochromate-alumina and dayfen. In addition to the extended reaction time, most of these processes suffer from drawbacks such as the use of corrosive acids and toxic metals that generate undesirable waste products. 

A suspension of thallium (III) nitrate in hexane reacts with epoxides to give the corresponding -hydroxy nitrate esters in good yield. The same reagent in acetonitrile has been used to synthesize a-nitratoketones from substituted acetophenones, 1,2-dinitrate esters from alkenes, and 1,3-dinitrates from ring-opening nitration of cyclopropanes. ... 

A suspension of thallium (III) nitrate in pentane at room temperature can react with alkenes to give vtc-dinitrate esters. Cyclohexene reacts with this reagent to give 1,2-cyclohexanediol dinitrate (85 %) (as a mixture of isomers) and 15 % cyclopentanecarboxaldehyde (hydride shift in the dethallation step). Some alkenes react extremely slowly with this reagent e.g. isomeric 5-decenes. 

To a stirred solution of chalcone (5 mmol) in trimethyl orthoformate (20 ml) was added Dowex 50 x 4 cation exchange resin (3 g). After stirring at room temperature for 20 h, the mixture was filtered into a solution of HTI (2.37 g, 6 mmol) in trimethyl orthoformate (10 ml) and kept for 12 h. It was then quenched with 10% aqueous sodium bicarbonate (25 ml) and extracted with dichloromethane. The combined organic layers were washed with water, dried and concentrated the residue was purified by column chromatography on silica gel (benzene), to afford methyl 2,3-diaryl-3-methoxypropanoates in 80-94% yield. This method was better than that reported with thallium (III) nitrate not only because this toxic reagent is avoided but also because yields were considerably higher. 

Jones reagent (1, 142-143).1 Phenols substituted by at least one alkyl group in the ortfio-position can be oxidized to / -quinones by a two-phase (ether/aqueous Cr03) Jones oxidation. Yields range from 30 to 85%, but the process is simple and more economical than use of Fremy s salt or thallium(III) nitrate. 

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 VS) whereas only the monocyclic 1,2-adducts were obtained from treatment of 3 with iodine azide, iodine isocyanate or iodine nitrate . 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. 

It is of interest to note in passing that In more recent work (ref.72), use has been made in synthesis of the transformation of chalcones to isoflavones with thallium(lll) nitrate. Thus, 6-acetyl-2,2-dimethyl-7-hydroxy-5-methoxychromanone was converted to the chalcone with 2,4-dibenzyloxybenzaldehyde. The O-acetyl derivative by treatment with the thallium reagent followed by acidic cyclisation gave a bischromanone structure. Selective reduction of the least hindered carbonyl group in the bischromanone, acidic dehydration of the resultant alcohol and final debenzylation with boron trichloride gave the linear isofiavone. 

Thallium(lll) nitrate has been used for this transformation (4, 496), but this reagent is toxic. 

The electrophilic substitution is the most characteristic reaction for these classes of compounds. Compound (21) undergoes standard electrophilic aromatic substitution reactions. Thus it forms the 6-bromo compound (58) with A7-bromosuccinimide and 6,7-dibromo compound (72) with the excess of the same reagent. It also forms the 6-nitro compound (67) with copper(II) nitrate trihydrate and 6,7-dinitro compound (68) with excess of nitronium tetrafluoroborate. The bis(trifluoro-acetoxy)thallium derivative (73) was formed from trithiadiazepine (21) and thallium(III) trifluoro-acetate in refluxing acetonitrile. Without isolation, (73) was directly converted into the pale yellow 6-iodo compound (74) with aqueous potassium iodide, into the 6-cyano compound (75) with copper(I) cyanide, and into methyl trithiadiazepine-6-carboxylate (76) with carbon monoxide and methanol in the presence of palladium chloride, lithium chloride, and magnesium oxide. Compound (21) is acetylated in the presence of trifluoromethanesulfonic acid (Scheme 7) <85CC396,87JCS(P1)217, 91JCS(P1)2945>. 

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