Nickel carbonyl insertion reactions

Figure F shows some acetylene insertion reactions. These, too, are similar to the olefin insertion reactions. The manganese and cobalt hydrocarbonyls again add. Chloronickelcarbonyl hydride, which I believe is an intermediate in many of the nickel carbonyl-catalyzed reactions, adds to olefins. Diborane and the aluminum hydrides also add.

I) Nickel, Palladium, and Platinum. For the elements of group VIII, an assessment of the relative reactivity for the carbonyl insertion reaction is available in the literature. For reaction (a), koss (x s , 2.3°C) of the process was found to decrease in the... 

A3-Pyrrolinones have also been obtained from metal-mediated cyclooligomerization processes in which concomitant hydrolytic or carbonyl insertion occurs. For example, tert-butyl isocyanide is converted in aqueous methanol by zerovalent nickel compounds e.g., Ni(t-BuNC)4, Ni(CO)4, into a di(alkylamino)-A3-pyrrolinone in moderate yield (Scheme 34). The reaction takes a different course in anhydrous methanol in which a di-tert-butylamino)ethylene derivative is formed, albeit in poor yield (Scheme 34).62... 

A3-Pyrroline formation with carbonyl insertion also occurs during the reaction of /V-sulfinylarylamines with diphenylcyclopropenone in the presence of nickel carbonyl (Scheme 36).64 Phenyl isocyanate does not give a pyrroline product under these reaction conditions, hence the SO-CO exchange probably occurs within an intermediate metallocycle. The reaction... 

The generality of the carbon monoxide insertion reaction is clear from reports that methylcyclopentadienyliron dicarbonyl (16), ethylcyclopentadienylmolylbde-num tricarbonyl (66), alkylrhenium pentacarbonyls (50), alkylrhodium dihalo carbonyl bisphosphines (34), allylnickel dicarbonyl halides (35), and mono-and di-alkyl derivatives of the nickel, palladium, and platinum bisphosphine halides (P), also undergo the reaction. The reaction of Grignard reagents (24), and of boron alkyls (51) with carbon monoxide probably takes place by the same mechanism. 

Probably the nickel carbonyl-catalyzed synthesis of acrylates from CO, acetylene, and hydroxylic solvent (78) involves an acetylene-hydride insertion reaction, followed by a CO insertion, and hydrolysis or acyl halide elimination. The actual catalyst in the acrylate synthesis is probably a hydride formed by the reversible addition of an acid to nickel carbonyl. 

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]. 

A relatively small number of carbon monoxide insertion reactions are known for alkyl or aryl derivatives of nickel. The oxidative addition of benzoyl chloride to Ni(PPh3)4 at 0°C was reported to give the corresponding phenyl derivative of nickel(Il) [reaction (c)], thus implying that the reverse of the carbonyl insertion from an unstable... 

As in the case of carbonylation, the reaction of alkynes with nickel metallacycles is often followed by reductive elimination. In some cases, the insertion product is stable and can be isolated (e.g., alkyne insertion in nickelalac-tones or fluorinated metallacycles, Equation (99)), but more frequently it is unstable and decomposes rapidly to afford substituted benzenes, dihydronaphthalenes,naphthalenes, or phenanthrenes. " The reaction of Ni(0) dippe complexes with biphenylene and alkynes in the presence of traces of O2 catalytically produces phenanthrenes, in a process that involves the intermediacy of a carbonickelacycle. " ... 

Murakami et al. reported a nickel-catalyzed alkyne/alkene insertion reaction into a C(carbonyl)-C(sp ) bond of cyclobutanones [21] and applied it to the enantioselective synthesis of benzobicyclo[2.2.2]octenones (Scheme 8.4) [22]. [2-f2] Cycloaddition of 1,2-divinylbenzene 24 with dichloroketene followed by... 

The catalytic potential of transition metal sulfides for abiotic carbon fixation was assayed. It was found that at 2000 bar and 250 °C, the sulfides of iron, cobalt, nickel, and zinc promote the hydrocarboxylation reaction via carbonyl insertion at a metal sulfide bound alkyl group. The results of the study support the hypothesis that transition metal sulfides may have provided useful catalytic functionality for geochemical carbon fixation in a prebiotic world [141]. 

The preparation of 7,7-d2-cholesterol in 1950 was the first example of deuterium incorporation into steroids via desulfurization of mercaptals with deuterated Raney nickel. A substantially modified version of this reaction subsequently became the first widely used method for site-specific insertion of two deuteriums in place of a carbonyl oxygen. This conversion consists of the preparation of a mercapto derivative (84 85), which usually... 

It is proposed that the reaction proceeds through (i) oxidative addition of a silylstannane to Ni(0) generating (silyl)(stannyl)nickel(n) complex 25, (ii) insertion of 1,3-diene into the nickel-tin bond of 25 giving 7r-allylnickel intermediate 26, (iii) inter- or intramolecular allylation of aldehydic carbonyl group forming alkoxy(silyl)nickel intermediate 27, and (iv) reductive elimination releasing the coupling product (Scheme 69). 

In general, carbonylation proceeds via activation of a C-H or a C-X bond in the olefins and halides or alcohols, respectively, followed by CO-insertion into the metal-carbon bond. In order to form the final product there is a need for a nucleophile, Nu". Reaction of an R-X compound leads to production of equivalent amounts of X", the accumulation of which can be a serious problem in case of halides. In many cases the catalyst is based on palladium but cobalt, nickel, rhodium and mthenium complexes are also widely used. 

Table I shows the effects of Mel/DME and CO/DME ratios in the feed gas on product yields. With increasing Mel/DME ratio both methyl acetate yield and selectivity increased. The yield of methyl acetate increased with an increase in the CO/DME ratio whereas its selectivity decreased. In the case of methanol carbonylation on Ni/A.C. catalyst, the product yield and selectivity were strongly affected by CO/MeOH ratio but not by Mel/MeOH ratio (14-16). The promoting effect of methyl iodide on the methanol carbonylation reached a maximum at a very low partial pressure, that is 0.1 atm or lower. However, both CO/DME and Mel/DME ratios were important for regulating the product yield and selectivity of the dimethyl ether carbonylation. This suggests that the two steps, namely, the dissociative adsorption of methyl iodide on nickel (Equation 4) and the insertion of CO (Equation 5) are slow in the case of dimethyl ether reaction.

The reaction of CO with some of the preceding organometallic compounds is rapid at room temperature and pressure and insertion of CO into the Ni—C bond results (equation 175).1445 In the case of the np3 ligand the first product isolated is a solid solution of the acyl derivative of nickel(II), [Ni(COR)(np3)]+, and a carbonyl complex of nickel(I), [Ni(CO)(np3)]+, in a 1 1 ratio. When this solid solution is dissolved in THF and EtOH, the pure acyl derivative (190) resulted. The acetyl derivative spontaneously loses CO on exposure to air restoring the original methyl derivative. 

A nickel-catalysed alkyne insertion between the carbonyl carbon and the -carbon of the cyclobutanone was achieved by combining a ketone-alkyne coupling reaction with a /3-carbon elimination process (Scheme 79).121 The reaction uses cyclobutanones as a four-carbon unit and provides access to substituted cyclohexenones. 

Eventually we formed carbonyls in the liquid phase by redox disproportionation of nickel and cobalt derivatives of organic thioacids. In the reaction between nickel(II) dithiobenzoate and carbon monoxide in the presence of HS ion we assumed the formation of a sulfur-bridged nickel(IV) complex (VII, 32). More recent investigations (84), however, have shown that half the nickel appears as a monomeric nickel(II) complex of the same empirical formulation, formed by insertion of a sulfur atom in the dithio ligand, the other half of the nickel being reduced to nickel(O) by the sulfide. 

The carbonylation of alcohols can proceed with formation of carboxylic acid by catalytic insertion of CO into the carbon-oxygen bond. An alternative reaction gives rise to oxalate or formate esters, when the CO is inserted into the oxygen-hydrogen bond. The members of the nickel triad carbonylate alcohols to give each of these products, and they will be discussed separately. 

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