With Aliphatic Halides

Diorgano tellurium compounds have been reacted with methyl iodide (Vol. IX, p 1076), ethyl iodide ethyl iodoacetate, cyclohexyl iodide , methyl bromide, allyl bromide , benzyl bromide , bromoacetone , bromomethyl phenyl ketone , a-bromocarboxylic acids , a-bromocarboxylic acid esters , methyl chloride, and benzyl chloride . 

Dialkyl, diaryl, unsymmetrical dialkyl, alkyl aryl, and unsymmetrical diaryl telluriums served as the tellurium-containing starting materials (Vol. IX, p. 1075). The reactions with methyl iodide and low molecular mass organic bromides proceed at 20° in organic solvents such as chloroform and methanol or in mixtures of the neat reagents.With aryl telluriums several days are required for completion of the reaction. Diaryl telluriums with ortho-substituents react only with difficulty. Bis[2,4,6-trimethylpheny 1] tellurium did not combine with methyl iodide. The reactions with ethyl iodide and a-bromocarboxylic acids are accelerated by gentle heating. 

Dimethyl (Propylthio)-ethynyl Telluronium lodide A mixture of 0.15 g (2.1 mmol) of methyl (propylthio)-ethynyl tellurium and 0.5 g (3.5 mmol) of methyl iodide is heated at 35° for 4 h, then kept in a stoppered flask at 20° for 2 days. The solid product is recrystallized from raethanol/diethyl ether yield 0.55 g (68%) m.p. 196-198° (dec.). 

Similarly prepared were the following alkynyl dimethyl telluronium iodides  

4-MethoxyphenyI Methyl Phenyl Telluronium Iodide 1.5 g (4.8 mmol) of 4-methoxyphenyl phenyl tellurium and 6.8 g (3 ml 48 mmol) of methyl iodide arc mixed and kept at 20° for 48 h. Diethyl ether is added to the mixture which is allowed to stand for 12 h. The mixture is then filtered and the solid dried yield 2.1 g (94%) m.p. 56°. 

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Analogous reactions have been shown to occur with aliphatic halides ... 

Fig. 18 Rate constants for the reaction of electrochemically generated iron(o), iron(i) and Co(i) porphyrins ( ) and aromatic anion radicals (A) with aliphatic halides as a function of their standard potentials, (Adapted from Lexa et al., 1981, 1988.)...

The possibility that substitution results from halogen-atom transfer to the nucleophile, thus generating an alkyl radical that could then couple with its reduced or oxidized form, has been mentioned earlier in the reaction of iron(i) and iron(o) porphyrins with aliphatic halides. This mechanism has been extensively investigated in two cases, namely the oxidative addition of various aliphatic and benzylic halides to cobalt(n) and chromiumfn) complexes. 

Synthesis ttf aliphatic carhoxySe acids, esters, and anodes. Sodium tetracarbonyl-ferrate(-ll) (1) reacts with aliphatic halides and tosylates to give anionic alkyltetra-carbonyliron(O) complexes (2). In the presence of carbon monoxide these undergo... 

An early example for cobalt-catalysed Mizoroki-Heck-type reactions with aliphatic halides by Branchaud and Detlefsen showed that an intermolecular substitution of styrene (2) could be achieved with [Co(dmgH)2py] (70) (dmgH = dimethylglyoxime monoanion) as catalyst in the presence of visible light. This radical reaction led selechvely to the substitution products when using stoichiometric amounts of Zn (27) and pyridine (31) as additives (Scheme 10.24) [52]. 

A more efficient and more generahy applicable cobalt-catalysed Mizoroki-Heck-type reaction with aliphatic halides was elegantly developed by Oshima and coworkers. A catalytic system comprising C0CI2 (62), l,6-bis(diphenylphosphino)hexane (dpph 73)) and Mc3 SiCH2MgCl (74) allowed for intermolecular subshtution reactions of alkenes with primary, secondary and tertiary alkyl hahdes (Scheme 10.25) [51, 53]. The protocol was subsequently applied to a cobalt-catalysed synthesis of homocinnamyl alcohols starting from epoxides and styrene (2) [54]. 

Nickelacycle 66 also reacts with aliphatic halides. Usually, allq lation reactions were carried without isolating any intermediate by treating anhydride 63 with 1.5 equiv each of Ni(COD)2 and ligand in THE at 23 °C for 5 h, followed by addition of excess alkyl halides (10-20 equiv)... 

In 1855, the Alsatian chemist Charles Adolphe Wurtz (1817-1884) observed the high reactivity of alkali metals with aliphatic halides (Eqs. 2.2a,b) and developed a C-C-coupHng method that was later named after him [3] ... 

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