Thallium trifluoroacetate, reaction with

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. ... 

Thallium(III), particularly as the trifluoroacetate salt, is also a reactive electrophilic metallating species, and a variety of synthetic schemes based on arylthallium intermediates have been devised.75 Arylthallium compounds are converted to chlorides or bromides by reaction with the appropriate cupric halide.76 Reaction with potassium iodide gives aryl iodides.77 Fluorides are prepared by successive treatment with potassium fluoride and boron trifluoride.78 Procedures for converting arylthallium compounds to nitriles and phenols have also been described.79... 

Somei and co-workers made extensive use of the Heck reaction with haloindoles in their synthetic approaches to ergot and other alkaloids [26, 40, 41, 240-249]. Thus, 4-bromo-l-carbomethoxyindole (69%) [26], 7-iodoindole (91%) (but not 7-iodoindoline or l-acetyl-7-iodoindoline) [40, 41], and l-acetyl-5-iodoindoline (96%) [41] underwent coupling with methyl acrylate under standard conditions (PdlOAc /PhsP/EtjN/DMF/100 °C) to give the corresponding (E)-indolylacrylates in the yields indicated. The Heck coupling of methyl acrylate with thallated indoles and indolines is productive in some cases [41, 241, 246]. For example, reaction of (3-formylindol-4-yl)thallium bis-trifluoroacetate (186) affords acrylate 219 in excellent yield [241], Similarly, this one-pot thallation-palladation operation from 3-formylindole and methyl vinyl ketone was used to synthesize 4-(3-formylindol-4-yl)-3-buten-2-one (86% yield). 

The synthesis of 7-methoxyindole was accomplished starting from 1-acetylindoline (34). Regioselec-tive introduction of iodine was achieved using thallium trifluoroacetate, then potassium iodide. Deacetylation and oxidation to the indole (35), followed by reaction with sodium methoxide in DMF, gave the... 

The synthesis of 7-methoxyindole was accomplished starting from 1-acetylindoline (34). Regioselec-tive intr uction of iodine was achieved using thallium trifluoroacetate, then potassium iodide. Deacetylation and oxidation to the indole (35), followed by reaction with sodium methoxide in DMF, gave the 7-methoxyindole (36) in 48% overall yield (Scheme 13). More recently, Somei et al have reported that treating the intermediate thallium species with copper(II) sulfate pentahydrate gives directly the l-acetyl-2,3-dihydro-7-hydroxyindole (37) in 42% yield (Scheme 14). It remains to be seen whether this is a general process. 

Taylor and cowoikers have studied the intramolecular capture of radical caticms from the thallium trifluoroacetate oxidation of arylalkanoic acids and arylalkanols. For example, 3-(3,4-dimethoxyphe-nyOpropionic acid (43) on treatment with thallium trifluoroacetate in trifluoroacetic acid containing a small amount of boron trifluoride etherate for a few seconds gave the oxidized products (44-46 Scheme 17), the exact yields dependent upon the reaction conditions and work-up. In analogous fashion, oxida-... 

Thalliuin(III) trifluoroacetate will also eliminate trifluoroacetic acid in reactions with compounds containing N—H bonds 40, 240). Thus, brief treatment of octaethylporphyrin in CHgCla and tetrahydrofuran with an excess of T1(02CCF3)3 followed by chromatography on deactivated alumina affords the complex shown in Fig. 10, This was the first unambiguous characterization of a thallium(III) porphyrin 240). 

It is important to note that cleavage of the 5-(acetamidomethyl) group with metal ions, such as thallium(III) trifluoroacetate, or with iodine may lead to alkylation of hydroxy groups,as well as of amide groups,P l via reactive acetamidomethanol intermediates. These side reactions are minimized by the use of glycerol as a scavenger. 

A porphyrin-specific reaction sequence of the propionic acid side chains consists of P-oxidation with thallium trifluoroacetate, followed by acid-catalyzed... 

Attention has also been called to thallium(III) salts for electrophilic metalation, and a number of procedures for synthesis of aromatic compounds via thallium intermediates have been reported." " A route to aryl iodides involves electrophilic substitution by thallium trifluoroacetate, followed by reaction with iodide ion ... 

Controlled fluorination of benzene is difficult, but it can be accomplished by a two-step thallation procedure. Benzene reacts with thallium tris(trifluoroacetate), TI(0C0CF3)3, to give an organothallium intermediate. Further reaction with potassium fluoride and boron trifluoride gives the aryl fluoride. Propose a mechanism for the first step, the thallation of benzene. 

Benzoic acid and substituted benzoic acids are readily thallated by thallium(III) trifluoroacetate. Subsequent reaction with palladium chloride and simple alkenes, allylic or vinyl halides, or vinyl esters result in the formation of isocoumarins eg ... 

Reaction with Copper Perchlorate, Ferric Perchlorate, Copper Tetrafluoroborate, or Thallium Trifluoroacetate... 

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