Nickel carbonyl, reactions with allylic halides

NEOPENTYL IODIDE, 51, 44 Nerol, 54, 70 Neryl chloride, 54, 70 Nickel carbonyl, precautions for handling, 52, 117 reaction with allyl halides,... 

The phase-transfer catalysed reaction of nickel tetracarbonyl with sodium hydroxide under carbon monoxide produces the nickel carbonyl dianions, Ni,(CO) 2- and Ni6(CO)162, which convert allyl chloride into a mixture of but-3-enoic and but-2-enoic acids [18]. However, in view of the high toxicity of the volatile nickel tetracarbonyl, the use of the nickel cyanide as a precursor for the carbonyl complexes is preferred. Pretreatment of the cyanide with carbon monoxide under basic conditions is thought to produce the tricarbonylnickel cyanide anion [19], as the active metal catalyst. Reaction with allyl halides, in a manner analogous to that outlined for the preparation of the arylacetic acids, produces the butenoic acids (Table 8.7). 

The role of the solvent in practically all of the reactions so far discussed is decisive. For example, allylic halides having electron-attracting substituents, such as methyl bromocrotonate, upon treatment with nickel carbonyl in hydroxylic solvents do not react with CO. Instead substitutive hydrogenation of the halogenated carbon atom occurs (55), while in ketonic solvents the products which might be expected from the carbonylation of normal allylic halides are obtained (50). 

K-Allylnickel ImBiles (2, 291), Walter and Wilke reported briefly that Ni(COD)2 is more reactive than nickel carbonyl in the reaction of allylic halides to form 71-allyl-nickel halides. The reaction proceeds below 0° and in quantitative yields. The method has not been used extensively since nickel carbonyl is commercially available. However, Semmelhack recommends use of Ni(COD)2 for the preparation of thermally sensitive a-allyinickel halides such as it-(2-carbocthoxyallyl)nickel bromide," which was prepared from ethyl 2-bromomethylacrylate with this nickel reagent in 76% yield. 

In 1970 Hashimoto published a report on the reaction of potassium hexacy-anodinickelate with organic halides in aqueous solutions [295]. Benzyl bromides were transformed into dibenzyl ketones in the presence of CO in a water-acetone solution. If the reaction was carried out in a water-methanol solution, trans-fi-bromostyrene was transformed into methyl trani-cinnamat. Surprisingly, cinna-maldehyde was also formed in a 10 % yield (Scheme 2.47). The reaction of nickel carbonyl [Ni(CO)4l with organic halides was studied by Bauld in 1963 [296]. Aryl iodides were reacted with Ni(CO)4 in methanol and produced the corresponding methyl benzoate in good yields. If the reaction was carried out in THF, arils were formed. The reaction of allyl halides with Ni(CO)4 in the presence of MgO will produce but-3-enylsuccinic acid [297]. 

Reactions of nickel carbonyl with allylic halides have been studied by Chiusoli (16). At 100° and 50 atm of carbon monoxide in the presence of... 

It has recently been suggested (19) that 7r-allylnickel complexes are intermediates in reactions involving allylic halides. Although ir-allylnickel chloride-triphenylphosphine (IX) is formed from allyl chloride and Ni(CO)3P(C6H5)3 without jrielding a carbonylation product (20), the dimeric 7r-allylnickel chloride (X) [prepared (13) by heating allyl chloride with nickel carbonyl in benzene solution] reacts rapidly with carbon monoxide to form butenoylnickel dicarbonyl chloride (XI) (Eq. 13). Moreover, this complex is converted by additional carbon monoxide into butenoyl chloride and nickel carbonyl (13), Eq. (14)... 

The synthesis of 1,5-dienes via the reaction of allyl halides and nickel carbonyl is now an indispensable process in synthetic organic chemistry. To our knowledge, it originates from the observation by Webb and Borcherdt (1951) that the reaction of l-chloro-2-butene or 3-chloro-l-butene with nickel carbonyl produced the dimeric 1,5-dienes in high yield. Later Corey and his... 

Palladium complexes also catalyze the carbonylation of halides. Aryl (see 13-13), vinylic, benzylic, and allylic halides (especially iodides) can be converted to carboxylic esters with CO, an alcohol or alkoxide, and a palladium complex. Similar reactivity was reported with vinyl triflates. Use of an amine instead of the alcohol or alkoxide leads to an amide. Reaction with an amine, AJBN, CO, and a tetraalkyltin catalyst also leads to an amide. Similar reaction with an alcohol, under Xe irradiation, leads to the ester. Benzylic and allylic halides were converted to carboxylic acids electrocatalytically, with CO and a cobalt imine complex. Vinylic halides were similarly converted with CO and nickel cyanide, under phase-transfer conditions. ... 

The development of the Grignard-type addition to carbonyl compounds mediated by transition metals would be of interest as the compatibility with a variety of functionality would be expected under the reaction conditions employed. One example has been reported on the addition of allyl halides to aldehydes in the presence of cobalt or nickel metal however, yields were low (up to 22%). Benzylic nickel halides prepared in situ by the oxidative addition of benzyl halides to metallic nickel were found to add to benzil and give the corresponding 3-hydroxyketones in high yields(46). The reaction appears to be quite general and will tolerate a wide range of functionality. 

Another clear example of an acetylene insertion reaction was reported by Chiusoli (15). He observed that allylic halides react catalytically with nickel carbonyl in alcoholic solution, in the presence of CO and acetylene, to form esters of cis-2,5-hexadienoic acid. The intermediate in this reaction is very probably a 7r-allylnickel carbonyl halide, X, which then undergoes acetylene insertion followed by CO insertion and alcoholysis or acyl halide elimination (35). Acetylene is obviously a considerably better inserting group than CO in this reaction since with acetylene and CO, the hexadienoate is the only product, whereas, with only CO, the 3-butenoate ester is formed (15). [See Reaction 59]. 

The carbonylation of allyl chloride with a nickel carbonyl catalyst appears to be the first useful example of an organic halide reaction to be reported (6). In alcohol solution at 50 atm pressure and 100°, mixtures of esters of 2- and 3-butenoic acid were obtained in about 50% yield with the 3-isomer predominating. Such high pressures and temperatures are probably not necessary for this reaction, however (7) ... 

Benzyl halides have been reported to react with nickel carbonyl to give both coupling and carbonylation (59). Carbonylation is the principal reaction in polar nonaromatic solvents, giving ethyl phenylacetate in ethanol, and bibenzyl ketone in DMF. The reaction course is probably similar to that of allylic halides. Pentafluorophenyl iodide gives a mixture of coupled product and decafluorobenzophenone. A radical mechanism has been proposed (60). Aromatic iodides are readily carbonylated by nickel carbonyl to give esters in alcoholic solvents or diketones in ethereal solvent (57). Mixtures of carbon monoxide and acetylene react less readily with iodobenzene, and it is only at 320° C and 30 atm pressure that a high yield of benzoyl propionate can be obtained (61). Under the reaction conditions used, the... 

The nickel-catalyzed carbonylation of allyl halides in the presence of alkynes and water produces 2,5-dienoic acids in good yields under very mild conditions (equation 25). This remarkable four-component reaction probably involves oxidative addition of the allyl chloride to the catalyst, followed by successive insertions of alkyne and CO, and finally hydrolysis. The carbon-carbon double bond derived from alkyne insertion is thus conjugated with the carbonyl group and generally has the (Z)-configuration. 

Nickel, palladium and copper catalysts can effect a variety of C — C bond-forming reactions P to the ester carbonyl via j8-zinc esters. These include 1,4-addition to a,jS-unsaturated carbonyl compounds (copper), arylation with aryl halides (palladium, nickel), allylation with allyl chloride (copper), and acylation with acyl chlorides (palladium, copper). " ... 

The hydroxycarbonylations (carboxylations) of alkyl, aryl, benzyl and allyl halides are from a retrosynthetic and mechanistic standpoint closely related. This type of reaction is widely used in organic synthesis [6], although a stoichiometric amount of salt by-product makes these methods less attractive on a large scale. The use of water-soluble catalysts for carbonylation of organic halides was scarcely studied in the past. Up to now palladium, cobalt, and nickel compounds in combination with water-soluble ligands have been used as catalysts for various carboxylations. 

In 2008 Bhanage s team reported on a copper-catalyzed carbonylative Sonogashira reaction of aryl iodides [68]. In this procedure, copper bis(2,2,6,6-tetra-methyl-3,5-heptanedionate) [Cu(TMHD)2] was used as the catalyst for this transformation and using NEta as a base. Alkynones were produced in good yields (Scheme 5.33). A nickel-catalyzed carbonylation of allyl halides and acetylenes was reported on by Moreto and colleagues [69]. Cyclopentane skeletons were produced in high yields and with controlled stereochemistry. 

Nickel carbonyl, however, does not react with acids to form such complexes. Nevertheless, it is possible that a reaction similar to (2) could occur with an intermediate alkyne-nickel carbonyl complex, giving rise to the formation of an alkenylnickel dicarbonyl halide, RCH=CH—Ni(CO)2X, which could then yield the unsaturated acid according to Eq. (3a) or (3b) 12). This reaction formally would resemble the carbonylation of allyl halides, discussed in Section II, C. Divinyl ketones may be formed as by-products of carbonylation 13), and the stereochemistry of addition to the acetylenic linkage is reported to be exclusively cis 13). 

Nickel carbonyl is also an eflFective dehalogenation agent. Apart from allyl halides (see above) cm-dihalides, e.g. dichlorodiphenylmethane, react with the carbonyl to form tetrasubstituted ethylenes (24). It is to be expected that carbonylation reactions would also occur in this case if the reaction were conducted under CO pressure. 

Application of this reaction to a,ct)-bisallylic halides makes the synthesis of medium and large rings possible. Treatment of l,l-bis(chloromethyl)-ethylene (CVII) with nickel carbonyl in tetrahydrofuran gives the dimer CVIII and trimer CIX in 11 and 54% yield, respectively (Corey and Sem-melhack, 1966). These products are derived by intermolecular coupling, followed by intramolecular coupling of allylic chlorides. The nine-membered carbocycle (CIX) was produced by the coupling of CVn and the dichloride... 

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