Active hydrogen compounds arylation

Cyanate/Cyanurate. When aryl cyanate esters are heated to 150 to 250°C, they cyclotrimerize to cyanuric acid esters (Fig. 3.62). They can be catalyzed by organo-metallic and active hydrogen compounds. When the monomer is a dicyanate such as bisphenol A dicyanate (Fig. 3.63), the result is a highly cross-linked heterocyclic polymer (Table 3.57). Using a novolac polycyanate has produced Tg and useful life over 300°C. 

A-Alkyl- and JV-aryl-bis(trifluoromethyl)ketenimines, (CFj)jC C NR, add active-hydrogen compounds such as primary amines across the C=C bond,... 

Aryl tellurium trichlorides and tribromides condense with methoxybenzene4,5, 1,3-dihydroxybenzene, and dimethylaniline6 to give unsymmetrical diaryl tellurium dihalides. The condensations occur with the hydrogen atom in the para-position to the activating group in the aromatic compound. Aryl tellurium triiodides did not react6. 

Barbituric acid itself does not possess any hypnotic properties. It is only when the two active hydrogen atoms at position 5 5 have the appropriate substituent e.g., alkyl or aryl groups) that the hypnotic activity is produced by the compound. The following cardinal points must be taken into consideration with respect to the structure-activity relationship amongst the barbiturates. These are ... 

On the other hand, the direct arylation of carbanionic species generated from substrates having relatively acidic hydrogens such as active methylene compounds and ketones can occur (mechanism B) [5,6]. Aryl halides are also capable of coupling directly with appropriately functionalized aromatic substrates and five-membered heteroaromatic compounds as formal carbon nucleophiles via cleavage of their unactivated C-H bonds [5,7-9]. The Fujiwra-Moritani reaction, which is the arylation of alkenes with arenes, is also useful for preparing arylalkenes without employing any halides (mechanism D) [10,11]. 

The active hydrogen in organometallic compounds containing P(aryl)3 ligands may be in the ortho-position of a phenyl ring. N.m.r. and deuteria-tion experiments have now demonstrated rapid equilibrium between such a complex in its initial form, hydrogen, and a a-phenyl bonded form, both for triphenylphosphine complexes, e.g. RuHCl(PPh3)3, and for several... 

Side chain fluonnaied aryl isocyanates are an important group of substances used in the manufacture of biologically active compounds The synthetic routes to the meta- and para trifluoromethylphenyl isocyanates permit the chlorine-fluonne exchange with hydrogen fluoride to proceed under moderate conditions and in a virtually quantitative manner (equation 22)... 

This method ensures the deposition of very reactive metal nanoparticles that require no activation steps before use. We shall review here the following examples of catalytic reactions that are of interest in line chemical synthesis (a) the hydrogenation of substituted arenes, (b) the selective hydrogenation of a, 3-unsaturated carbonyl compounds, (c) the arylation of alkenes with aryl halides (Heck reaction). The efficiency and selectivity of commercial catalysts and of differently prepared nanosized metal systems will be compared. 

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