Aryl bismuth compounds

Sterically crowded aryl bismuth compounds synthesis and characterization of bis 2,4,6-tris(tri luoromethyl)phenyl bismuth chloride and tris 2,4,6-tris(trifluoromethyl)phenyl bismuth. /. Organomet. Chem. 402 55-66. 

Quaternary bismuth compounds have not found extensive use ia industry or ia organic synthesis. In manifold studies of organobismuth(V) compounds as oxidi2ing and arylating agents, such quaternary bismuth compounds as (CgH )4Bi02CCH2, (CgH )4Bi02SCgH4CH2-4, and... 

Cyclic triarylbismuth(III) compounds also undergo the Pd-catalyzed cross-coupling reaction with benzoyl chloride (Scheme 27) [42]. The exocyclic aryl group was selectively transferred to form 4-methylbenzophenone in good yield. Bismuth-containing products could not be isolated except for the cyclic bismuth compound possessing a SO2 moiety, for which cyclic bismuth chloride was isolated in 86% yield. 

Aryl chlorides can also be used as coupling partners for azabismocine reagents 2. In the coupling reaction with aryl chlorides, Pd(PPh3)4 was not an efficient catalyst, and Pd(OAc)2/l,l,-bis(diphenylphosphino)ferrocene (dppf) combination was found to be effective [54]. Not only the arylation, but also methylation, alkenylation and alkynylation reactions can be accomplished by using the corresponding bismuth compounds (Scheme 35). The addition of CsF improved the product yields. However, electron-rich aryl chlorides were unable to be coupled efficiently under these reaction conditions. 

This method has also been a general method for the synthesis of triorganoantimony and -bismuth compounds. The antimony or bismuth anion (RjM", M = Sb, Bi) reacts with organic halides, which can be either aryl halides such as 18 in equation 21 , or alkyl halides (equations 22 and 23 ), Dimetallated triorganometallic compounds such as 19 which are useful as ligands for transition metals are available from this method (equation 24). ... 

Various alkyl and aryl substituted pentaorganoantimony compounds are known, however pentaorganobismuth compounds have been limited to aryl substituted compounds. Most of this type of compound has been synthesized by transmetallation from Grignard reagents or organolithium reagents to antimony and bismuth centers. 

Both alkyl and aryl derivatives are accessible by this method with similar ease. Monohalobismuthine R2BiX is the main product when 1 mol of BiXs is reacted with 2 mol of R Bi. If the molar ratio is reversed, dihalobismuthine RBiX2 is obtained as the major product. Diethyl ether, tetrahydrofuran, benzene, dichloromethane and chloroform are the solvents of choice for this reaction. This reaction is, however, essentially based on the equilibration among four different bismuth compounds, R BiX3 (n=0-3), in a given solution. Thus, recrystallization from a suitable solvent is necessary to obtain an analytically pure compound. 

The first example of C-arylation with pentavalent bismuth compound is... 

According to Waters results,27,28 the formation of aryl-metal compounds on decomposition of arenediazonium chlorides in the presence of metals such as mercury, antimony, bismuth, lead, and tin also occurs by way of radicals, in contrast to the Nesmeyanov reaction. 

Other methods of preparing tertiary bismuthines have been used only to a limited extent. These methods iaclude the electrolysis of organometaUic compounds at a sacrificial bismuth anode (54), the reaction between a sodium—bismuth or potassium—bismuth alloy and an alkyl or aryl haUde (55), the thermal elimination of sulfur dioxide from tris(arenesulfiaato)bismuthines (56), and the iateraction of ketene and a ttis(dialkylainino)bismuthine (57). 

Both alkyl and aryl metals have been studied, but not a very wide range of compounds. Several studies of triphenylarsene and triphenylstibine have been done. Methyl and ethyl compounds of arsenic, germanium, mercury, bismuth, and lead essentially complete the list. In virtually all cases the results have been clouded by difficulties in effecting chemical separation without altering the product distribution. The results do, nonetheless, lead to valid and important conclusions. 

C-arylation with bismuth(V) compounds, 9, 444 CH-acids, in carbonylative cyclizations, 11, 429 Enols, in Co-assisted alkylation of propargylic alcohols, 11,126 Enone-dienes, in reductive cyclizations, 10, 502 Enones... 

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