Metathesis compounds

Another interesting transformation is the intramolecular metathesis reaction of 1,6-enynes. Depending on the substrates and catalytic species, very different products are formed by the intramolecular enyne metathesis reaction of l,6-enynes[41]. The cyclic 1,3-diene 71 is formed from a linear 1,6-enyne. The bridged tricyclic compound 73 with a bridgehead alkene can be prepared by the enyne metathesis of the cyclic enyne 72. The first step of... 

A precipitation reaction occurs when two or more soluble species combine to form an insoluble product that we call a precipitate. The most common precipitation reaction is a metathesis reaction, in which two soluble ionic compounds exchange parts. When a solution of lead nitrate is added to a solution of potassium chloride, for example, a precipitate of lead chloride forms. We usually write the balanced reaction as a net ionic equation, in which only the precipitate and those ions involved in the reaction are included. Thus, the precipitation of PbCl2 is written as... 

Other tri alkyl and triaryl compounds of the type R2SbY2, where Y is a pseudohaUde or a group such as NO, CIO, or S SO, have been prepared. They are usually obtained from the dihahdes by metathesis with a silver salt, eg ... 

In addition to the tri alkyl- and triaryldihaloarsoranes there are a number of compounds of the type R2ASY2, where Y is a pseudohalide, nitrate, carboxy, or other negative group. They are usually prepared from tri alkyl- or triaryldibromo- or dichloroarsoranes by metathesis. Thus dia2idotrimethyiarsorane [21121-84-6], C H AsN, has been prepared in the following manner (151) ... 

A number of other tetraarylbismuth compounds Ar4BiY, where Y is a group, such as NO , C10 4, OCN , N , etc, have been prepared from the chloride by metathesis. Two tetraalkylbismuth compounds have been reportedly prepared by means of the following synthesis (164) ... 

Ethers, esters, amides and imidazolidines containing an epithio group are said to be effective in enhancing the antiwear and extreme pressure peiformance of lubricants. Other uses of thiiranes are as follows fuel gas odorant (2-methylthiirane), improvement of antistatic and wetting properties of fibers and films [poly(ethyleneglycol) ethers of 2-hydroxymethyl thiirane], inhibition of alkene metathesis (2-methylthiirane), stabilizers for poly(thiirane) (halogen adducts of thiiranes), enhancement of respiration of tobacco leaves (thiirane), tobacco additives to reduce nicotine and to reduce phenol levels in smoke [2-(methoxymethyl)thiirane], stabilizers for trichloroethylene and 1,1,1-trichloroethane (2-methylthiirane, 2-hydroxymethylthiirane) and stabilizers for organic compounds (0,0-dialkyldithiophosphate esters of 2-mercaptomethylthiirane). The product of the reaction of aniline with thiirane is reported to be useful in the flotation of zinc sulfide. 

The perfluorovmylcadmium compounds react with electrophiles as expected [144] (equation 111) and readily undergo metathesis with cuprous halides [145] (equation 112)... 

Only few examples of functionalized copper reagents have been prepared The perfluoroallyleopper reagent was prepared via metathesis of the corresponding perfluoroallylcadmium compound [146] (equation 159) Reaction of the allyl... 

Perfluoroacetylentc copper compounds also can be prepared via metathesis of the corresponding zinc or cadmium reagents with copper(l) bromide. The zinc or cadmium reagents are formed from the corresponding pentachloroperfluo-roalkaneorl lodoperfluoroalkyne [727 747] (equations 168 and 169)... 

The perfluoroalkylthio- and pentafluorophenylthiocopper compounds have been used for the introduction of the -SRj- and -SAtf group into molecules [264, 265, 266, 267] for increased biological activity Trifluoromethylthiocopper has been prepared via metathesis of AgSCFj with copper(I) halides [264] and the... 

Trifluoromethyl-substitutedazimines are surprisingly stable compounds. They are accessible by 1,3-dipole metathesis from tnfluoromethyl-substituted azomethine imines and certain nitroso compounds [187, 188] On photolysis, an electrocyclic ring closure first gives the triaziridines, which are stable at room temperature. On heating above 80-100 C, a valence tautomenzation takes place and azimines are formed [189] (equation 43). 

M(C 0)s and other Mo and W compounds catalyse alkene metathesis hy the formation of... 

Alkene metathesis for the synthesis of carbo- and heterocyclic compounds 97YGK1101. 

Acyclic diene molecules are capable of undergoing intramolecular and intermolec-ular reactions in the presence of certain transition metal catalysts molybdenum alkylidene and ruthenium carbene complexes, for example [50, 51]. The intramolecular reaction, called ring-closing olefin metathesis (RCM), affords cyclic compounds, while the intermolecular reaction, called acyclic diene metathesis (ADMET) polymerization, provides oligomers and polymers. Alteration of the dilution of the reaction mixture can to some extent control the intrinsic competition between RCM and ADMET. 

Other RhX(CO)(PPh3)2 compounds can be made as shown in Figure 2.23 metathesis with an alkali metal halide or pseudohalide is often convenient, but the most versatile route, as with the iridium analogues, is a two-stage process in which the fluoro complex is first prepared, the fluorine then being readily displaced. 

The Metathesis of Unsaturated Hydrocarbons Catalyzed by Transition Metal Compounds... 

Since then, the metathesis reaction has been extended to other types of alkenes, viz. substituted alkenes, dienes and polyenes, and to alkynes. Of special interest is the metathesis of cycloalkenes. This gives rise to a ring enlargement resulting in macrocyclic compounds and eventually poly-... 

The discovery of the metathesis reaction is also of importance from a theoretical and fundamental point of view, and has contributed to the development of new ideas about reactions of alkenes in the presence of transition metal compounds. 

Mutual metathesis of a cyclic and an acyclic alkene provides still more possibilities in synthesizing organic compounds. For instance, cycloalkenes are cleaved by ethene into a,co-dienes. The reaction of 1,5-cyclooctadiene with ethene gives 1,5,9-decatriene (18) norbornene reacts with 2-butene to yield 1,3-dipropenylcyclopentane (30) ... 

Hafnium compounds as catalysts, 188 1,5-Hexadiene, metathesis of, 134 Hexyne, metathesis of, 136, 154 Hydrocarbons, see also specific compounds Federal emission control requirements, 59, 60... 

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