Triarylbismuth oxides

Soluble triarylbismuth oxides, (AraBiO) , which oxidize activated alcohols and triphenylphosphine (in 60% yields) are formed efficiently by a sonochemical technique. 

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... 

Recent comparative studies (intermolecular competition experiments using two different bismuth(V) oxidants and intramolecular competition experiments with unsymmetrically substituted bismuth(V) oxidants [80, 81]) revealed that the substituents affect the triarylbismuth(V) oxidants as follows ... 

Scheme 17 Oxidation of alcohols with triarylbismuth(V) oxidants [81]...

For instance, the relative oxidizing ability of Ar3BiCl2 (in the Ar3BiCl2/DBU system) was found to be in the order Ar = /j-nitrophenyl > /j-(trifluoromethyl) phenyl > o-methyl-p-chlorophenyl > p-chlorophenyl > o-methylphenyl > phenyl > p-methylphenyl. On the basis of these findings, new efficient triarylbismuth(V) oxidants have been prepared and some reagents are now commercially available. 

Diaryl tellurides undergo facile ligand-transfer oxidations with [bis(acyl-oxy)iodo]arenes in chloroform to give stable diaryltellurium dicarboxylates 12 (Scheme 7) [23]. Similar ligand-transfer oxidations of triarylbismuthanes and triarylstibanes with BAIB in dichloromethane leading to Bi(V) and Sb(V) diacetates 13 and 14 have also been reported [24,25]. The triarylbismuth diacetates were employed for high yield Cu(II)-catalyzed arylations of a series of aryl-amines [24]. 

N-Alkylation of saccharin can be achieved with KF in ionic liquid (bmimIPFg <2004JCR276>. For N-arylation of saccharin one can use cupric acetate with a triarylbismuth <1996TL9013>, /i-tolyllead triacetate <1996JOC5865>, or an arylboronic acid in the presence of an oxidant <1998TL2933, 2001TL3415>. 

The /V-arylalions of aliphatic, heterocyclic or aromatic amines is achieved either by treatment with pentavalent triarylbismuth derivatives and catalytic copper species or by treatment with a trivalent triarylbismuthane and stoichiometric amounts of copper diacetate that acts both as an oxidant and as the catalyst305. 

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... 

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... 

Barton and co-workers have investigated the use of triarylbismuth dihalides and related compounds for synthetic purposes. These compounds can be used for the oxidation or arylation of a variety of alcohols, enols, amines, phenols, thiols, hydrazine, nitroalkanes and others (Sections 5.2.4, 5.4.3 and 5.5.2). 

Triarylbismuthine A -tosylimides react with benzaldehyde, benzoyl chloride and phenyl isocyanate to give A -tosylimine, A-tosylamide and A -tosylurea derivatives, respectively [91CL105] (Section 5.5.2.3). The imides oxidize secondary and benzylic alcohols to carbonyl compounds, sometimes accompanied by the concurrent formation of a diaryl(A -tosylamino)bismuthine [96JCR(S)24] (Section 5.2.4). When treated with acetic acid, the imides are converted to the corresponding triarylbismuth diacetates and sulfonamides (Scheme 3.9). 

Bis(acyloxy)iodo]arenes are useful for the oxidation of organic derivatives of bismuth and antimony [543,544], Triarylbismuthanes 452 react with (diacetoxyiodo)benzene in dichloromethane under mild, neutral conditions to afford pentavalent triarylbismuth diacetates 453, which can be isolated in good yields (Scheme 3.179) [543], Triarylstibines 454 react with PhI(OAc)2 under similar conditions to afford triarylan-timony(V) diacetates 455 [544],... 

Another interesting possibility for a special P-C coupling reaction involves the interaction of triarylbismuths with secondary phosphine oxides using PdCl2/2,2 -bipyridine (Scheme 22). ... 

AU these authors proposed that the mechanism bears some similarity to the copper-mediated arylation of amines from triarylbismuth compounds, described by Barton et al. [273]. Thus, the reaction would proceed via the formation of a cupric acetate complex with the nucleophile followed by a transmetallatimi with arylboronic acid playing the role of the triarylbismuth, before affording the N-arylated compound by reductive elimination. This last step would be facilitated by prior oxidation by dioxygene of a copper II intermediate to a copper IB intermediate [266-270, 274]. Some authors reported that the addition of molecular... 

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