Triaryl special

Trialkyl esters of phosphonic acid exist ia two structurally isomeric forms. The trialkylphosphites, P(OR)2, are isomers of the more stable phosphonates, 0=PR(0R)2, and the former may be rearranged to resemble the latter with catalytic quantities of alkylating agent. The dialkyl alkylphosphonates are used as flame retardants, plasticizers, and iatermediates. The MichaeUs-Arbusov reaction may be used for a variety of compound types, including mono- and diphosphites having aryl as weU as alkyl substituents (22). Triaryl phosphites do not readily undergo the MichaeUs-Arbusov reaction, although there are a few special cases. 

Shell Chemical has a process that does both the Oxo reaction and hydroformyiation in one step in the same reactor. They use a special catalyst, thought to be cobalt modified with a trialkyl or triaryl phosphine ligand— but they are holding this one pretty close to the vest. Overall yields are 70-80%, with straight-chain alcohols representing greater than 80%. Major by-products are paraffins that are recovered and used to make olefins and then recycled back as feed. This process can also use internal olefins (with the double-bond somewhere besides the alpha position) and yield similar normakiso alcohol ratios. ... 

Aminations of five-membered heterocyclic halides, such as furans and thiophenes, are limited. These substrates are particularly electron-rich. As a result, oxidative addition of the heteroaryl halide and reductive elimination of the amine are slower than for simple aryl halides (see Sections 4.7.1 and 4.7.3). In addition, the amine products can be air-sensitive and require special conditions for their isolation. Nevertheless, Watanabe has reported examples of successful couplings between diarylamines and bromothiophenes [126]. Triaryl-amines are important for materials applications because of their redox properties, and these particular triarylamines should be especially susceptible to electrochemical oxidation. Chart 1 shows the products formed from the amination of bromothiophenes and the associated yields. As can be seen, 3-bromothiophene reacted in higher yields than 2-bromothiophene, but the yields were more variable with substituted bromothiophenes. In some cases, acceptable yields for double additions to dibromothiophenes were achieved. These reactions all employed a third-generation catalyst (vide infra), containing a combination of Pd(OAc)2 and P(tBu)3. The yields for reactions of these substrates were much higher in the presence of this catalyst than they were in the presence of arylphosphine ligands. 

Intramolecular Hydrogen Transfer. It is possible to transfer groups from the metal to ligand by insertion reactions, but a rather special case of transfer reactions is one between certain ligands and the metal atom in which a hydrogen atom is initially transferred and is then subsequently lost. Such reactions are especially important for triarylphosphines and triaryl phosphites.30 Some examples are the following ... 

Shi et al. [161-164] studied a different reaction of an array of triphenylmethane and triarylmethane derivatives such as alkanes, alkenes, alkynes, phosphonates, phosphonic acids and esters, dialkylamines, triaryl acetic acid, triaryl acetonitriles, triaryl acetates, and tetraarylmethanes and published a review of their work [65]. Mainly from product studies they proposed the special case of di-Jt-methane and oxa-di-7u-methane reactions [165], viz. a,a-elimination gives a biaryl and the corresponding carbenes and operates in polar and nonpolar sol-... 

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