Triphenylbismuth oxide

Triphenylbismuth oxide [7173-99-1/, C gH BiO, has been prepared from triphenylbismuth dicyanide [41083-16-3], C2QH25B1N2, and mercuric oxide (151), and from triphenylbismuth dichloride and moist silver oxide (152). The ir and Raman spectra of this compound suggest that it is polymeric and has Bi—O—Bi bonds (153). Triphenylbismuth dihydroxide, and triarylbismuth hydroxide haUdes, eg, triphenylbismuth hydroxide chloride... 

Triphenylbismuth dichloride, 4 33 Triphenylbismuth difluoride, 4 27 Triphenylbismuth dimethacrylate, 4 33 Triphenylbismuthine, 4 26 Triphenylbismuth iodide isocyanate, 4 32 Triphenylbismuth iodide azide, 4 32 Triphenylbismuth oxide, 4 32 Triphenylcarbamate... 

The reaction of dimedone (39) with tetraphenylbismuthonium derivatives and BTMG gave the a,a-diphenyl derivative (40). But when dimedone (39) was treated with triphenylbismuth carbonate, an ylide (41) was obtainedP This ylide was later isolated as a stable crystalline compound. This ylide (41) can also be prepared by reaction of the sodium salt of dimedone either with triphenylbismuth dichloride or with triphenylbismuth oxide. Similarly, Meldrum s acid gave the corresponding bismuthonium ylide with triphenylbismuth carbonate and with triphenylbismuth dichloride.3 36 uch ylides can also be made by decomposition of the appropriate dicarbonyl diazonium derivative in the presence of triphenylbismuthane catalysed by bis(hexafluoroacetylacetonato)copper (II) 37 These ylides react with aldehydes to give cyclopropanes, dihydrofurans and a,p-unsaturated carbonyl... 

When treated with iodine pentafluoride, triphenylbismuthane gives triphenylbismuth difluoride but no evidence for the formation of bismuth(V) derivatives was found in the reactions with tris(4-fluorophenyl)bismuthane and tris(trifluoromethyl)bismuthane. Fluorine-aryl (or alkyl) exchange takes place in these cases instead of oxidative fluorination.139140... 

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... 

Pentavalent derivatives of triphenylbismuth such as p,-oxobis(chlorotriplienylbismudi) (1) and triphe-nylbismuth carbonate (2) have been developed recently as oxidizing agents which cleave a-glycols into the corresponding carbonyl derivatives (equation 1). Aldehydic products do not undergo further oxidation. Reagent (1) also oxidizes saturated ilcohols as well as allylic and benzylic alcohols, whereas (2) selectively oxidizes allylic alcohols in the presence of saturated alcohols. ... 

Triphenylbismuth carbonate (2) displays remarkable chemoselecdvity, aUowing alcohol oxidation in the presence of benzenethiol, pyrrolidine, indole, aniline, dimethyl aniline and 3-pyrolidinocholesta-3,S-diene. The diol moiety in (3) is cleaved selectively without oxidizing the dithioacetal function (equation 3). The rate of the stoichiometric oxidative cleavage of ciJ-cyclohexane-l,2-diol to adipic aldehyde with Ph3BiC03 is faster than that of the trans isomer, suggesting the formation of a cyclic organobismuth intermediate (4 Scheme 1). ... 

Clearly there are easily oxidizable groups other than alcohols which might be found within a particular structure, and which can interfere with the oxidative introduction of a carbonyl group. Not surprisingly reagents have been developed which will show chemoselectivity for the oxidation of the alcohol function in such systems. Triphenylbismuth carbonate and p.-oxo-bis(chlorotriphenylbismuth) have been reported as such a chemoselective reagent, and will oxidize alcohols in the presence of other easily oxidized species such as benzenethiol, indole and pyrrole (Section 2.9.3). This reagent also cleaves 1,2-diols. 

Oxidation. Triphenylbismuth carbonate suspended in CH2CI2 is a heterogeneous oxidant for a variety of functional groups. Allylic alcohols are efficiently oxidized to the corresponding unsaturated aldehydes or ketones, even in the presence of a thiol, which is itself oxidized by this reagent to a disulfide, cis- and Irani-1,2-Glycols are cleaved to dialdehydes hydrazones are oxidized to diazocompounds oximes are cleaved to ketones and 1,2-dialkylhydrazines are oxidized to azo compounds. Phenylhydrazones, semicarbazones, tosylhydrazones, aromatic and aliphatic amines, enamines, and enol ethers are inert to 1. 

How can we assess the thermochemical data presented in Table 1 Many were obtained by static-bomb calorimetry. Regrettably, this technique is clearly unsuitable to deal with these substances due to the ill-defined composition of the combustion products (see the discussion in References 13 and 28). The formation of nonstoichiometric oxides upon combustion all but precludes the experimental rigor demanded of the combustion calorimetrist. This fact, by itself, allows us to question the reliability of the values shown for all of the trialkyl compounds and for triphenylantimony. Although the results for triphenylbismuth found by static and rotating-bomb calorimetry overlap within their error bars, this has been suggested to be fortuitous ... 

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... 

In the case of 2,6-disubstituted phenols, the nature of the bismuth reagent, the nature of the alkyl substituents and the reaction conditions determined the outcome of the reactions. 2 Thus, in the reactions of 2,6-dimethylphenol (19) with pentaphenylbismuth (4) or with tetraphenylbismuthonium derivatives under basic conditions, ortho C-phenylation resulted in the formation of 6-phenylcyclo-hexadienone (20) in good yield. On the other hand, oxidative dimerisation took place in the reaction of 2,6-dimethylphenol with triphenylbismuth carbonate to afford the diphenoquinone (21) quantitatively 25... 

The behaviour of the most sterically hindered 2,6-di-rerr-butylphenol (25) and its derivatives was very dependent upon the reaction conditions. In the presence of a base favouring electron-transfer (such as BTMG), oxidation reactions took place with triphenylbismuth dichloride or triphenylbismuth carbonate leading to the diphenoquinone (26). Para-phenylation with formation of (27) was observed for the first time in the reaction of the potassium phenolate of 2,6-di-re rr-butylphenol with triphenylbismuth dichloride and in the reaction of the phenol (25) with tetraphenylbismuthonium tosylate in the presence of BTMG. Even ortho- and para-phenylation with concomitant de-rerr-butylation occurred in the reaction of the potassium salt of 2,4,6-tri-re r/-butylphenol with triphenylbismuth dichloride. 2... 

In the case of polyhydroxylic phenols, perphenylation occurred. Thus, phloroglucinol (28) reacted with triphenylbismuth carbonate to give a mixture of 2,4,6-triphenylphloroglucinol (29) and 2,2,4,5-tetraphenylcyclopent-4-en-l,3-dione (30).24 The dione (30) is formed from (29) by phenylation, decarboxylation and oxidation. When a large excess of triphenylbismuth carbonate (5 mol equiv.) was used, the dione (30) was the only isolated product in 60% yield. In contrast, the reaction of phloroglucinol with pentaphenylbismuth led to a complex mixture.25... 

Arylthiols were converted to mixed arylphenylsulfides by reaction with pentaphenylbismuth (4) or with tetraphenylbismuthonium trifluoroacetate (6). Oxidation products were also formed in minor amounts (<15%). On the other hand, thiols were readily converted to the corresponding disulfides by treatment either with triphenylbismuth dichloride (3) or with triphenylbismuth carbonate (5) in the presence of sodium hydride.2533... 

Triphenylbismuth carbonate generally does not react with amines, although phenyl transfer to the amino functionality was first observed during an attempt of oxidation of the hydroxyl function of an aminoalcohol by triphenylbismuth carbonate in chloroform. It also reacted with iV-phenylhydro-xylamine under neutral or basic conditions to give diphenylnitroxyl and iV,iV-diphenylacetamide after reductive acetylation (29-33%). No reaction was noted between triphenylbismuth carbonate and nitrosobenzene. High-yielding -arylation was found in the reaction of amino-alcohols with triarylbismuth diacetate in methylene dichloride under reflux. 5... 

In the reaction of alcohols with the various types of pentavalent organobismuth compounds, 0-phenylation is usually disfavoured, oxidation taking place preferentially. However, in the case of the reaction of glycols with triphenylbismuth diacetate, an apical-equatorial chelation (93) was suggested to explain the facile mono-O-phenylation which is observed. By contrast, diapical chelation (94) takes place with monofiinctional alcohols, and the ensuing reductive process leads to oxidation. 

Hexafluoropropene oxide is also a good reagent for the nucleophilic formation of the Bi-F bond in triphenylbismuth) V) compounds [99JFC(93)103],... 

Triphenylbismuthine is oxidized by A-bromosuccinimide, lead tetraacetate or benzoyl nitrate to give triphenylbismuth bromo(succinimide), diacetate and... 

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... 

Various oxybis(triphenylbismuth) compounds can be prepared by the reaction of oxybis(triphenylbismuth) dichloride and silver salts [72JOM(36)323]. A combination of silver(I) oxide and sulfonic acids can also be used instead of silver sulfonates [88JOM(342)185],... 

A mixture of silver oxide (0.5 mmol), oxybis(triphenylbismuth) dichloride (0.5 mmol), chloroform (20 ml) and methanol (5 ml) was stirred for 15 min. To this mixture was added benze-nesulfonic acid (1 mmol) and it was stirred for a further 3 h at room temperature. It was then filtered, washed with methanol (5 ml), and the filtrate was concentrated under vacuum. By adding ethyl acetate to the concentrate, oxybis(triphenylbismuth) bis(benzenesulfonate) was obtained as a fine white powder. The compound was filtered and crystallized from ethyl acetate. Yield, 58%, m.p. 155-157°C (decomp.) [88JOM(342)185]. 

Treatment of anhydrous oxybis(triphenylbismuth) perchlorate with oxygen-donor bases results in the formation of pentacoordinate cationic complexes [73IC944]. Dimethyl sulfoxide, pyridine iV-oxide, triphenylphosphine oxide and triphenylarsine oxide are commonly employed ligands. 

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