Alkyls manganese

Acylation reactions can also be greatly improved in this way, with t-alkyl- or sec-alkyl-manganese reagents reacting with acid chlorides in excellent yields [123]. The related addition-elimination to 3-ethoxy-2-cyclohexenone is also improved, resulting after acidic aqueous workup in 3-methyl-2-cyclohexenone [125]. The perilla-ketone 126 was prepared in an improved yield using copper(I) catalysis (Scheme 2.58) [129]. 

Scheme 2.59. Copper-catalyzed alkylation of alkyl manganese reagents.

Whether coordination of the carbon monoxide is required before insertion can take place in all these examples is not clear. But since it is required in the alkyl-manganese pentacarbonyl reaction, it is not unreasonable to expect the same to be true in the other cases. 

Scheme 14.4. Vinyl halides react with alkyllithium to afford vinyllithium, and then a reaction with MnCl2 affords the manganeselithium compound. RI produced from the formation reaction of vinyllithium reacts with the manganeselithium compounds to afford the alkylmanganese compounds. The alkyl group of the alkyl-manganese compounds is easily eliminated. Then the coupling reaction of one vinyl group eliminated produces mole of diene [83].

A further example of the use of a polymer support in distinguishing between identical functional groups within the same molecule is outlined in Scheme 16. Yields are reasonable when alkyl manganese reagents are used. 

Mn(>/ -C5Cl5)(CO)3, and Mn( / -CH2Ph)(CO)4. Irradiation at ambient temperature results in both CO loss and the homolysis of the alkyl-manganese bond ... 

Acyl chlorides have been converted into unsymmetrical ketones by reaction with alkyl halide at a cadmium anode- - and by reaction with alkyl manganese iodide.Cyclopropylalkyl (or vinyl) ketones are formed in moderate yields by reaction of an acyl halide with cyclopropyltrimethylsilane. ... 

The yield of ketones can be sometimes improved by working in the presence of copper salts as catalyst (1 to 5%), especially in the case of methyl and s- or t-alkyl-manganese chlorides (Scheme 13.18). 

Reactions 33 and 35 constitute the two principal reactions of alkyl hydroperoxides with metal complexes and are the most common pathway for catalysis of LPOs (2). Both manganese and cobalt are especially effective in these reactions. There is extensive evidence that the oxidation of intermediate ketones is enhanced by a manganese catalyst, probably through an enol mechanism (34,96,183—185). 

Unsymmetrical dialkyl peroxides are obtained by the reaction of alkyl hydroperoxides with a substrate, ie, R H, from which a hydrogen can be abstracted readily in the presence of certain cobalt, copper, or manganese salts (eq. 30). However, this process is not efficient since two moles of the hydroperoxide are consumed per mole of dialkyl peroxide produced. In addition, side reactions involving free radicals produce undesired by-products (44,66). 

Manganese cyclopentadienyl tricarbonyl (as Mn) Marble/calcium carbonate Mercury (alkyl compounds) (as Hg)... 

Within group (i), square-planar EtPt(CO)(AsPh3)Cl inserts more rapidly than six-coordinate EtIr(CO)2(AsPh3)Cl2. In THE at 40°C, the relative k s are 9 and 1. Comparison of group (ii) alkyl carbonyls reveals the order MeMn(CO)5 > CpMo(CO)3Me > CpFe(CO)2Me. The ratios of the k s are 23 I and 100 1, respectively, in THF at 25° and 50.7°C. The higher reactivity of manganese than of molybdenum is a consequence of the relative entropies, whereas the lowest reactivity of iron is caused by its Jff (Table III). 

Kinetic 37, 50-52, 97, 168) and stereochemical 54, 191, 192) investigations on the carbonylation of manganese alkyls and the decarbonylation of manganese acyls were already discussed in Sections III-V. The original finding (50) that the rate of CO insertion follows second-order kinetics has now been qualified 192). At higher pressures of CO (>15 atm) the first-order rate law [Eq. (23)] is obeyed. 

Homocoupling of alkyl halides in aqueous media can be mediated by manganese/cupric chloride to give the dimerization products in good yield. Cross-coupling can also be controlled to give the desired... 

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