Triphenylbismuth synthesis

Barton and coworkers have explored the arylation of various nucleophiles including nitroalkanes using bismuth reagents.105 Reaction of 2-nitropropane with triphenylbismuth carbonate gives 2-nitro-2-phenylpropane in 80% yield.106 Recently, this arylation has been used for the synthesis of unusual amino acids. Arylation of a-nitro esters with triphenylbismuth dichloride followed by reduction gives unique a-amino acids (Eq. 5.68).107... 

Arylation. Although some oxidations with triphenylbismuth carbonate occur with quantitative conversion to (Cf,H,)jBi, some proceed with Bi-C cleavage. Although attempts to trap aryl radicals have failed, this cleavage can be used in a synthesis for transfer of an aryl group from Bi to N.1 Examples ... 

The allylic alcohol (273) has also been used in a preparation of 15-oxo-15,20S-dihydrocatharanthine (275a), required for partial synthesis of anhydro-vinblastine (q.v.).125 Oxidation of (273) could be achieved by a variety of oxidizing agents, of which triphenylbismuth carbonate appeared to be the best (Scheme 39). Oxidation of the allylic alcohol group was followed by Michael addition of Nb to the... 

The first studies on the application of pentavalent organobismuth derivatives in organic synthesis focused on oxidation reactions. In the course of these studies, when Barton et al treated quinine with triphenylbismuth carbonate (5), the reaction led to a rather modest yield of the expected quininone (34%). Using an excess of the reagent (5) afforded a good yield of a mixture of diastereo-isomeric a-phenylated ketones (75%). 3... 

Other enolised compounds were also easily arylated. Such was the case of P-ketosulfones, which reacted easily with triphenylbismuth carbonate (5) to afford the corresponding a-phenyl-P-ketosul-fones. This reaction was put to good use in an efficient synthesis of isoflavanone and isoflavone... 

Other stabilized anions that were successfully C-arylated include the anions of nitroalkanes, a-methyl-a-nitrocarboxylic acid derivatives, esters, triphenylmethane, indole and scatole. Nitroalkanes gave high yields of the a-C-aryl derivatives. Ita the presence of BTMG, 2-nitropropane reacts with triphenylbismuth dichloride or tetraphenylbismuthonium p-toluenesulfonate to lead to a-nitrocumene (86 or 77% respectively). The reaction using triphenylbismuth dichloride and TMG was applied to the synthesis of a-methyl-a-phenylglycine via arylation of a-nitropropionic acid esters. ... 

Synthesis of compound (90) (case of p-naphthol) corresponding to the postulated intermediate in the 0-phenylation reaction was performed by the base-catalysed reaction of p-naphthol with triphenylbismuth bistrifluoroacetate. However, after decomposition, this reaction led only to the products of C-phenylation.24J0 (Scheme 6.12) Moreover, the C-phenylation is a fast reaction which can be completed at room temperature, or below, when the 0-phenylation under neutral or acidic conditions requires long periods of reflux of the benzene solutions. 

Moreover, the synthesis and good stability of the covalent carbon-bismuth compound in the case of acetone, 2-oxopropyltriphenylbismuthonium perchlorate, excluded this type of intermediate as a common pathway, although this view was questioned by Suzuki et The reaction of the sodium salt of acetylacetone with triphenylbismuth dichloride led to a bismuthonium salt (37) decomposing slowly at room temperature to give eventually 3-phenylpentane-2,4-dione (35). ... 

Metathesis of triarylbismuth dichloride with a variety of metal salts such as fluoride, azide, cyanide, carboxylates and sulfonates has been used frequently for the synthesis of triarylbismuth(V) compounds of the type Ar Bi Y 2, where Y is the corresponding anionic group (Section 3.1.1). The reaction of triphenyl-bismuth dichloride with mercuric chloride in an alkaline medium leads to triphenylbismuthine, while treatment of triphenylbismuth dicyanide with mercuric oxide results in the formation of triphenylbismuthine oxide (Section... 

Synthesis of oxybis(triphenylbismuth) diperchlorate-bis(triphenylphosphine oxide)... 

Oxybis(triphenylbismuth) dichloride has been used as the reagent for oxidation and arylation in organic synthesis (Sections 5.2.4 and 5.4.3). 

Crystalline bismuthine imides bearing an A-sulfonyl group have been prepared by the condensation of triphenylbismuth difluoride with A,A-bis(tri-methylsilyl)sulfonamides or of triarylbismuth dichloride with sulfonamides [93JFC(63)179]. The latter combination is also applicable to the synthesis of trianylbismuthine A -acylimides [99OM2580]. 

Among other dehydrogenation reagents, we should mention triphenylbismuth carbonate (97 7o yield of diphenyldiazomethane, Barton et al., 1979), and sodium hydride in THF, which was used by Padwa et al. (1983 a) to prepare (E)-l,4-di-phenyl-4-diazobut-l-ene (2.74) from (E)-l,4-diphenylbut-3-en-l-one A -tosylhydra-zone (2.73) (2-29). It was also used by Krebs et al. (1984) for the synthesis of diazocyclopentane, -hexane and -heptane derivatives with two methyl groups at the two C-atoms in the positions a- and a - to the diazo C-atom. At the same time, Cullen et al. (1984) published the synthesis (2-30) of the corresponding diazocy-clopentene, 4-diazo-3,3,5,5-tetramethylcyclopentene (2.78). They added first an equivalent of bromine and afterwards triphenylphosphine to the corresponding hydrazone 2.76. The triphenylphosphanylidene derivative 2.77 was isolated and heated for two hours without solvent at 185 °C. 

This example describes the synthesis of a particularly high molecular weight polymer. A catalyst solution is prepared by dissolving TaCls (0.10 mmol, 36 mg) and triphenylbismuth (0.10 mmol, 44 mg) in toluene (5.0 mL), followed by aging at 80 °C for 15 min. Using this catalyst solution, polymerization is carried out in the same way as the case with the Tads catalyst alone. Polymer yield = 100% and = 4.0x 10 . ... 

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