Triarylbismuth diacetates

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]. 

A large number of aniline derivatives have been synthesized using a combination of the procedures discussed above209,328-336. In addition, resin-bound triarylbismuth diacetates (80a-c) were used as multidirectional linkers to form arylation products in yields and conditions similar to those reported for the solution-phase A-arylations (Figure 18)337. 

Ester derivatives of a-amino acids underwent A-arylation with arylbismuth reagents under mild conditions338-341. The arylation was performed with both the free amino esters and with the protonated amino ester salts, although most of the latter reacted in only moderate yields. High yields of A,A-diphenylated products were obtained with 1.2 equivalents of triarylbismuth diacetate A,A-diphenylated products were also obtained by a two-step process (equation 77)339. 

FIGURE 18. Novel resin-bound triarylbismuth diacetate as iV-arylation reagent... 

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... 

The arylation of lower aliphatic alcohols was observed when the copper-catalysed decomposition of triarylbismuth diacetate was carried out in simple alcohols, used as solvent (20 mL per mmole of bismuth reagent). The yields of alkyl aryl ethers (based on the bismuth reagent) ranged from 60 to 95% for primary and secondary alcohols, but only 9% were obtained in the case of t rt-butyl alcohol.Under stoichiometric conditions, the 0-phenylation of 3-p-cholestanol by triphenylbismuth diacetate (1 equiv.) was not significantly improved upon addition of copper diacetate. 5 Different copper compounds, such as Cu(OAc)2, CuCl2, CuCl or metallic copper, can be used as effective catalysts. 

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). 

As is the case for cross-coupling reactions, arylstannanes and aryltriaUcoxysilanes can be substituted for boronic acids in this method, but would appear to offer few advantages. A number of other, usually Cu(II)-catalysed, reagents can be used to arylate azoles and indoles, of which diaryliodonium salts are the most useful. Aryllead triacetates and triarylbismuth diacetates may find very occasional use, but A-cyclopropylation using tricyclopropylbismuth with cupric acetate is possibly more interesting. ... 

ArsBi —> ArsBi(OAc)2. Triarylbismuth diacetates are readily obtained using... 

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],... 

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. 

Various 3-(3 - and 4 -substituted phenyl)-4-hydroxycoumarins were easily accessible by reaction of 4-hydroxycoumarins with triarylbismuth dichloride and triarylbismuth dinitrate under basic conditions or with triphenylbismuth diacetate (47) under neutral conditions. In the latter reaction, the best yields were obtained when the reaction was performed in methylene dichloride in the dark.40... 

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