Nickel-acid reaction

Nickel Salts and Chelates. Nickel salts of simple organic acids can be prepared by reaction of the organic acid and nickel carbonate of nickel hydroxide reaction of the acid and a water solution of a simple nickel salt and, in some cases, reaction of the acid and fine nickel powder or black nickel oxide. 

Two techniques, electrochemical reduction (section IIl-C) and Clem-mensen reduction (section ITI-D), have previously been recommended for the direct reduction of isolated ketones to hydrocarbons. Since the applicability of these methods is limited to compounds which can withstand strongly acidic reaction conditions or to cases where isotope scrambling is not a problem, it is desirable to provide milder alternative procedures. Two of the methods discussed in this section, desulfurization of mercaptal derivatives with deuterated Raney nickel (section IV-A) and metal deuteride reduction of tosylhydrazone derivatives (section IV-B), permit the replacement of a carbonyl oxygen by deuterium under neutral or alkaline conditions. 

Stereoselective) additions of nucleophiles to 5-alkylidene Meldmm s acid as displayed in Scheme 17 (Section 8.11.6.1.3) <2006TA2957, 2007AGE4964> and to the carbonyl group of 2,2-dimethyl-l,3-dioxan-5-one (Scheme 47, Section 8.11.6.3.3) either in a three component transformation <2006OL3689> or in a nickel-catalyzed reaction... 

A mixture of 15 gms. of phthalic anhydride and 22 gins, of resorcinol is ground in a mortar. It is then transferred to a nickel or cast-iron vessel, and heated in an oil bath to 180°. At this temperature 7 gms. of powdered fused zinc chloride (see p. 509) are added, with stirring, during the course of 10 minutes. The temperature is raised to 210°, and maintained at this point until the liquid, which gradually thickens, becomes solid, for which 1—2 hours are required. The cold melt is removed from the vessel with a knife or chisel, powdered, and boiled 10 minutes with 200 c.cs. of water and 10 c.cs. of cone, hydrochloric acid. This treatment eauses the solution of zinc oxide and basic zinc chloride. The fluorescein is filtered off, washed with water until the filtrate no longer shows an acid reaction it is dried on a water bath. 

Phenylthioalkylation of silyl enol ethers. Silyl enol ethers of ketones, aldehydes, esters, and lactones can be alkylated regiospecifically by a -chloroalkyl phenyl sulfides in fhe presence of a Lewis acid. Zinc bromide and titanium(IV) chloride are the most effective catalysts. The former is more satisfactory for enol ethers derived from esters and lactongs. ZnBr2 and TiCL are about equally satisfactory for enol ethers of ketones. The combination of TiCL and Ti(0-f-Pr)4 is more satisfactory for enol ethers of aldehydes. Since the products can be desulfurized by Raney nickel, this reaction also provides a method for alkylation of carbonyl compounds. Of more interest, sulfoxide elimination provides a useful route to a,B-unsaturated carbonyl compounds. 

Whereas palladium(0)-catalyzed reactions of dialkyl fumarate and dialkyl maleate yield reaction products identical to those obtained from the phosphane-modified nickel-catalyzed reactions (vide supra), analogous palladium(0)-catalyzed reactions with ( )-but-2-enoic or (E)-cinnamic acid derivatives lead to different products to the nickel-catalyzed reactions, i.e. in the palladium-catalyzed reactions formal distal cleavage of but-2-enoic MCP occurs to provide methyl tra i-2-methyl-4-methylenecyclopentanecarboxylate (12, R = Me) and methyl trans-4-methylene-2-phenylcyclopentanecarboxylate (12, R = Ph), respectively." Yields and stereoselectivities are slightly higher with palladium(O) catalysts. When R = Me, 7.4% of the C-C double bond isomerization product, methyl traM -2,4-dimethylcyclopent-3-enecarboxylate (13, R = Me), is additionally obtained, raising the combined yield of cyclocodimers to 49.9%. With methyl (jE )-cinnamate, analogous isomerization only occurs upon workup, i.e. distillation of the crude product. 

When cyclic alkene substrates are employed, the [3 -I- 2]-cycloaddition methodology provides a powerful tool for performing cyclopentaannulation reactions. However, the nickel-catalyzed reactions of this kind only proceed with difficulty in many cases. For example, annulation of cycloalk-2-enones, such as cyclopent-2-enone, can only be performed at moderate yields when triethylborane is added as activating Lewis acid. ... 

On the basis of the mechanism described on page 871, the base-pairing interaction between the anticodon on the incoming tRNA and the codon in the A site on mRNA determines which amino acid is added to the polypeptide chain. Does the amino acid attached to the tRNA play any role in this process This question was answered in the following way. First, cysteine was attached to its cognate tRNA. The attached cysteine unit was then converted into alanine by removing the sulfor atom from the side chain in cysteine in a reaction catalyzed by Raney nickel the reaction removed... 

The thioxo compounds 109 and 111 are readily desulfurized by shaking with Raney nickel. This reaction provides a link for the establishment of orientations of compounds obtained by condensation reactions of a-keto esters (RCOC02R ) and the corresponding a-keto aldehydes (RCOCHO) with 2,3-diaminopyridines. Thus the 0x0 compounds obtained from the former reactions may be converted into the products from the latter reactions by successive treatment with phosphorus pentasulhde and Raney nickel. For example, the compound 114, obtained as the only product from the condensation of 2,3-diamino-5-bromopyridine with ethyl pyruvate in strongly acid solution (see Section II2B), has been converted to the thioxo compound 115, which on desulfurization yields compound 116, identical with that obtained from the condensation of the pyridine with pyruvaldehyde in neutral solution (see Section II2A). 

There has been a wide-ranging review of transmetalation reactions of arenes concentrating on the use of boron-containing compounds. The reaction of arylboronate esters and related compounds with alkyl halides is catalysed by copper(I) formation of an aryl—copper intermediate followed by an 5N2-type reaction with the alkyl electrophile is likely. Palladium complexed with a diimine is an excellent catalyst in the phenylation reaction of Michael acceptors with phenylboronic acid so as to yield products such as (16). The nickel-catalysed reaction of phenylboronic acid with styryl epoxides has been shown to yield a-substituted alcohols such as (17). 

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