C-Carboxylation

C) Carboxylic adds For aryl-substituted alcohols, such as benzyl alcohol, oxidation readily gives the corresponding add (c/. p. 336). 

Fig. 2. Functional groups on modified polyacrylamides (a) formed by reaction with dimethylamine and formaldehyde (Mannich reaction) (b), quatemized Mannich amine (c), carboxylate formed by acid or base-cataly2ed hydrolysis or copolymerization with sodium acrylate and (d), hydroxamate formed by...

Figure 3. Schematic representation of the common functional groups that are present on carbon (a) quinone (b) phenol (c) carboxyl (d) carbonyl (e) lactone (f) hydrogen.

Write the general formula of each of the following types of compounds, using R to denote an organic group (a) amine (b) alcohol (c) carboxylic acid (d) aldehyde. 

Figure 46-5. Variations in the way in which proteins are inserted into membranes. This schematic representation, which illustrates a number of possible orientations, shows the segments of the proteins within the membrane as a-helicesand the other segments as lines. The LDL receptor, which crosses the membrane once and has its amino terminal on the exterior, is called a type I transmembrane protein. The asialoglycoprotein receptor, which also crosses the membrane once but has its carboxyl terminal on the exterior, is called a type II transmembrane protein. The various transporters indicated (eg, glucose) cross the membrane a number of times and are called type III transmembrane proteins they are also referred to as polytopic membrane proteins. (N, amino terminal C, carboxyl terminal.) (Adapted, with permission, from Wickner WT, Lodish HF Multiple mechanisms of protein insertion into and across membranes. Science 1985 230 400. Copyright 1985 by the American Association for the Advancement of Science.)...

Smith and co-workers have employed NHC 81 to catalyse the 0- to C-carboxyl transfer of a range of oxazolyl carbonates 80, forming 82 with the generation of a C-C bond at a quaternary centre with good catalytic efficiency [27], This transformation presumably proceeds via the generation of an intermediate carboxyazolium species, and has been utihsed as a component of domino multi-component reactions [28], as well as the rearrangement of indolyl and benzofuranyl carbonates (Scheme 12.15) [29]. 

A, amino acceptor C, carboxylate acceptor L, lipophilic region SL, small lipophilic region... 

Crystals of complex 112 suitable for an X-ray structure determination were obtained on cooling a solution in pentane to — 30 °C. The structure determined is shown in Fig. 7.9. The most remarkable structural feature of 112 is that the gallium center is connected to the zirconium through two different c-carboxylic bridges. One of them contains the cyclo-C6Hg system, which is t]1-bonded to gallium and r 2-coordinated to zirconium. It is noteworthy that carbon atom C-2 is planar tetracoordinate. It is connected to four neighboring atoms in the c-plane, specifically to carbon atoms C-l and C-3 and to both metal centers [175]. 

The C -carboxyl group of an a-amino acid is suitably protected as required or alternatively, an amino-containing derivative with appropriate modification is used. 

Quinn, P.J., and Dawson, R.M.C., 1969, Interactions of cytochrome c and [ C] carboxylated cytochrome c with monolayers of phosphatidylcholine, phosphatidic acid and cardiohpin, Biochem. J. 115 65-75. 

Soil. Smith (1974) studied the degradation of C-ring- and C-carboxyl-labeled dicamba in moist prairie soils at 25 °C. After 4 wk, >50% of the herbicide degraded to the principal products... 

Ray A, Okouneva T, Manna T, Miller HP, Schmid S, Arthaud L, Luduena R, Jordan MA, Wilson L. (2007) Mechanism of action of the microtubule-targeted antimitotic depsipeptide tasidotin (formerly ILX651) and its major metabolite tasidotin C-carboxylate. Cancer Res 67 3767-3776. 

N,N -Diphenylformazan-C-Carboxylic Acid or N, N Diphenylformazyl Formic Acid (For mazylameisensaure in Ger),... 

The Addition of C02 to Aldehydes and Ketones O-Hydro-C-carboxyl-addition... 

The Kolbe-Schmitt reaction produces O- and C-carboxylation through the reaction of carbon dioxide with sodium benzenolate at 125° ... 

Sodium benzenolate absorbs carbon dioxide at room temperature to form sodium phenyl carbonate (O-carboxylation) and, when this is heated to 125° under a pressure of several atmospheres of carbon dioxide, it rearranges to sodium 2-hydroxybenzoate (sodium salicylate). However, there is no evidence that this reaction is other than a dissociation-recombination process, in which the important step involves electrophilic attack by carbon dioxide on the aromatic ring of the benzenolate ion (C-carboxylation) ... 

C-Carboxylation of enolates.1 Carboxylation of potassium enolates generated from silyl enol ethers is not regioselective because of extensive enolate equilibration. Regiospecific C-carboxylation of lithium enolates is possible with carbonyl sulfide in place of carbon dioxide. The product is isolated as the thiol methyl ester. If simple esters are desired, transesterification can be effected with Hg(OAc)2 (8, 444). Carboxylation of ketones in this way in the presence of NaH and DMSO is not satisfactory because of competing alkylation of the enolate.2 Example ... 

C carboxyl carbons of PMMA. In order to get stronger signals, PMMA with 20% of13 C-labelled carboxyl carbons has been used. 

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