Halides active

Organic Halides. Alkyl halides and aiyl halides, activated by election withdrawing groups (such as NO2) in the ortho or para positions, react with alkyleneamines to form mono- or disubstituted derivatives. Product distribution is controlled by reactant ratio, metal complexation or choice of solvent (16,17). Mixing methylene chloride [75-09-2J and EDA reportedly causes a mnaway reaction (18). 

Probably the most common aromatic nucleophilic displacement reactions involve the displacement of Hal from a halide activated by electron-withdrawing groups, e.g. (80) ... 

The arylation of organyl tellurolates, restricted first to aryl halides activated by electron-withdrawing groups,2 or requiring special conditions such as heating in HMPA in the presence of Cul, or photostimulation in liquid ammonia,ijggjj achieved successfully with non-activated aryl halides under normal conditions. ... 

Alkylation of Alkali Metal Cyanides by Alkyl Halides Activated in the a-Posi-tion by a Double Bond. When a mixture consisting of 4 to 8 moles of an alkyl halide activated in the apposition by a double bond is heated with 1 mole of alkali metal ferrocyanide, several alkylation products of the ferrocyanide anion can be isolated from the reaction mixture (12). The relative proportions of the tetra-, penta-, and hexaalkylated complexes can be varied by varying the alkyl halide to ferrocyanide ratio and the time of reaction. When potassium ferrocyanide is alkylated with benzyl bromide at a ratio of 4 alkyl halides to ferrocyanide anion, short reaction times favor the tetraalkylated complex an 8 to 1 ratio and long reaction times favor the hexaalkylated complex of the alkylating agents tested benzyl bromide provided the fastest alkylation ... 

Transalkylation Reaction. The alkylation reaction of potassium ferrocyanide with alkyl bromides activated at the a-carbon by a double bond (14) gave in each case good conversions to the corresponding isonitrile complexes. Since this method is limited to alkyl halides activated at the Qj-carbon by a double bond, it was of interest to develop a general method for the preparation of aliphatic isonitrile complexes. 

Organic Halides. Alkyl halides and aryl halides, activated by electron withdrawing groups (such us NO-) in the ortho or para positions, react with alkyleneamines to form mono or disubstituled derivatives. 

Among the halides that react through this process are unactivated aromatic and heteroaromatic halides, vinyl halides, activated alkyl halides [nitroalkyl, nitroallyl, nitro-benzyl and other benzylic halides substituted with electron-withdrawing groups (EWG) as well as the heterocyclic analogues of these benzylic systems] and non-activated alkyl halides that have proved to be unreactive or poorly reactive towards polar mechanisms (bicycloalkyl, neopentyl and cycloalkyl halides and perfluoroalkyl iodides). 

Other electrophiles include acylium ions produced from acid chlorides, carbocations from tertiary halides or secondary benzylic halides, activated enones, and epoxides all in the presence of Lewis acid. In each case the new bond is highlighted in black. 

Polymerizations which are second order in Lewis acid have also been observed, including self-initiated polymerizations with AlBrj [181], and isobutene polymerizations initiated by alkyl esters and halides activated by TiCU [175,182],... 

AMINO-THIOETHERS aryl halides + active methylene 13-14... 

Acyl halides, activated esters, carboxylic anhydrides and iV-acylimidazoles react with alkylidenephos-phoranes to yield acylated ylides. " - " ... 

Sonogashira coupling can be elegantly and efficiently carried out copper-free [17], Similarly to sp -carbon halides, activated olefins can be linked with terminal alkynes [18]. 

Asymmetric modifications of hydrovinylation are one of the earliest examples of successful asymmetric transition metal catalysis. After optimization of various dimerization and codimerization reactions using phosphane modified nickel catalysts, the first examples of asymmetric olefin codimerization were reported with n-allylnickel halides activated by organoaluminum chloride and modified by chiral phosphanes7. Thus, codimerization of 2-butene with propene using n-allylnickel chloride/A]X, (X = Cl, Br) in the presence of tris(myrtanyl)phosphane gives low yields of (—)-( )-4-methy 1-2-hexene (I) with 3% ee7,7 . 

Similarly, asymmetric metal-catalyzed hydrovinylation of various other olefins has been investigated, usually catalyzed by nickel systems prepared from Ni(IJ) salts or / -allylnickel halides, activated by Lewis acids such as ethylaluminum dichloride or diethylaluminum chloride, and modified by chiral phosphanes. Surveys of these results are found in more general reviews11-12 and reviews dealing preferentially with this subject -5-7-13 - A... 

Cockeram and Rapp have evaluated the kinetics of silicide coatings on Ti [103] and have used a halide-activated pack-cementation method to form boron- and germanium-doped silicide coatings on orthorhombic alloy substrates [104]. The coatings greatly decreased the cyclic oxidation kinetics and microhardness measurements did not indicate diffusion of oxygen into the substrate. 

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