Reaction with other Organometallic Compounds

Sodium tetraethylaluminate and lithium tetrabutylaluminate alkylate oxiranes stereo- and regioselectively. In the case of aliphatic oxiranes, the reaction takes place on the less-substituted carbon atom, while in the case of a phenyl substituent, it occurs at the benzylic position, always with inversion. In the presence of a catalytic quantity of nickel salt, the reaction is accelerated considerably. 

With trans-alkenyltrialkylaluminates, /1-hydroxy-tranx-alkenes are obtained (Eq. 290).  

The reaction of lithium trialkylalkynylborate and oxiranes has been described.A small amount of air initiates the 1,5-addition of the organo-borane and the oxirane by a radical mechanism to produce allenic derivatives (Eq. 

Oxiranes are transformed by tris(ethylthio)borane to sulfur-containing derivatives.With selenoboranes, terminal or a,)3-disubstituted epoxides yield 3-hydroxyse enides trisubstituted epoxides give allyl alcohols. 

In the presence of MeaSiK, cyclohexene can be hydroxyethylated in the allyl position with oxirane (Eq. 292).  

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Indium-mediated allylation of trialkyl(difluoroacetyl)silane 70 in aqueous media gives homoallylic alcohol 71 exclusively (Scheme 60). Both water and THF are essential for the allylation reaction. It is worth noting that homoallylic alcohol 71 is formed exclusively under these reaction conditions. On the contrary, enol silyl ether 72 is a major product of the fluorinated acylsilanes reaction with other organometallic compounds than indium via a Brook rearrangement and defluorination. Indium-mediated allylsilylation of carbonyl compounds provides a facile route to 2-(hydroxyethyl)allylsilanes. The allene homologs are similarly prepared (Scheme 61).244,244a... 

The reaction has also been performed with other organometallic compounds, for... 

Many other methods have been used to prepare bonded phases these include esterification of the surface silanol groups with alco-Tiols, or conversion of the silanol groups to Si—Cl using thionyl chloride, followed by reaction with an organometallic compound. If you are interested, there are details in the textbooks by Knox or by Hamilton and Sewell. 

Transmetallation reactions of Grignard reagents with other organometallic compounds are rare. An example is shown here [70] other transmetallations have been briefly reported [71]. 

Nucleophilic ring-opening of oxiranes by lithium dialkylcuprates occurs at the sterically less-hindered side and the corresponding alcohol is formed.The reaction can be carried out under mOd conditions and the side-reactions observed with other organometallic compounds can be avoided. The mechanism of the transformations has been treated in detail. With MejCuLi the reaction proceeds stereoselectively and the new C-C bond is formed on the side opposite the C-0 bond of the oxirane (Eq. 

Organosilicon compounds can be prepared by reaction of silicon halides with other organometallic compounds. The first such synthesis (1865) was that by Friedel and Crafts270 who heated silicon tetrachloride with dimethyl-zinc in a sealed tube at 200° ... 

PdCl2(MeCN)2 and [(ii -allyl)PdCl]2, or even simple palladium salts allows one to perform the reactions under milder conditions, at lower temperatures in less-polar solvents (acetone, THF, ether, even benzene). The elementary steps of the catalytic cycle - oxidative addition and especially transmetal-lation - are accelerated, which is quite important as the reactivity of organo-tin compounds is relatively low compared with other organometallic compounds used in cross-coupling reactions [50]. 

The bimetallic mechanism is illustrated in Fig. 7.13b the bimetallic active center is the distinguishing feature of this mechanism. The precise distribution of halides and alkyls is not spelled out because of the exchanges described by reaction (7.Q). An alkyl bridge is assumed based on observations of other organometallic compounds. The pi coordination of the olefin with the titanium is followed by insertion of the monomer into the bridge to propagate the reaction. 

Other reactions of aryl organometallic compounds are treated with their aliphatic analogs Reactions 12-24-12-34. 

Activation energies of thermal reactions in organometallic compounds have unfortunately not yet been measured. It would seem that the Group VI carbonyls would offer the best possibilities for such measurements, since their reactions are not complicated by competitive reactions. Unfortunately it cannot be said with confidence that these compounds are representative of aU other organometallic compounds as well. 

Reacts with many metals to give hydrogen, sometimes violently. With non-metals pyrophoric hydrides may result. Frequently initiates explosive reactions between other substances. Violent reactions with many non-metal and some metal halides and oxyhalides, also with many organometallic compounds. Many metal nonmetal-lides produce toxic, flammable or pyrophoric gases on contact with diprotium monoxide. 

Grignard reagents react with halides of less electropositive metals to give other organometallic compounds. The less electropositive (more electronegative) metals include Hg, Zn, Cd, Si, and the nonmetal P. An example of this type of reaction is... 

A solulion of CuCl in HCI absorbs carbon monoxide, forming copperil) carbonyl chloride. Cu(CO)Cl H 0. This reaction, which is used In gas analysis, is Indicative of the ability of copper to combine with carbon monoxide. Evidence for a true carbonyl is limited to the observation that if hot carbon monoxide is passed over hot copper, a metallic mirror is produced in the hotter parts of the tube. Other organometallic compounds include Ihe very unstable methyl copper, CHiCu. phenyl copper. C<,H5Cu, and bixchlurucopper acetylene CjHrtCuCIi . 

A thermographic material with only one heat-sensitive component is prepared by reaction of an organometallic compound such as phenylmercury(II) nitrate with a thiourea derivative.230 The product is ball milled and coated in a binder such as poly(vinyl acetate). Other organometallic compounds disclosed are those of bismuth, tin, gallium and germanium combined with a variety of sulfur-containing compounds such as thioamides and xanthates. 

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