Alkyl carboxylic acid

Alkylation of the 1,2,4-triazole ring by alkyl radical species has been achieved reaction of 1-methyl-1,2,-4-triazole 37 with alkyl carboxylic acids in the presence of a silver catalyst gave the corresponding 2-alkylated triazoles 38a-e in moderate yields (Equation 9 and Table 1) <2001TL7353>. 

The reaction of benzo-2-furancarboxylic acid with thiosemicarbazide under microwave conditions enables the use of an equivalent amount of phosphorus oxychloride and a short reaction time <2003SC2891 >. Moreover, solvent-free conditions are achieved when acidic alumina is used as dehydrating agent under microwave heating in the reaction of alkyl carboxylic acids with thiosemicarbazide <2000SC3031>. 

Racemic fra .s-A--benzyl-2.5-bis-(ethoxycarbonyl)pyrrolidine has been resolved via its dicarboxylic acid, followed by subsequent transformation to offer (2R,5R)-21 or (25,5S -21. The absolute configuration of the alkylated carboxylic acids indicates that the approach of alkyl halides is directed to one of the diastereotopic faces of the enolate thus formed. In the following case, the approached face is the 57-face of the (Z)-enolate. By employing the chiral auxiliary (2R,5R)-21 or its enantiomer (25.55)-21. the (/ )- or (S)-form of carboxylic acids can be obtained with considerably high enantioselectivity (Table 2-4). 

From the archival enthalpies of formation of the other species, the enthalpy of formation of cyclohexyl methyl amine is —145.4 kJmoH. From equation 11, the enthalpy of formation of the corresponding salt is —501.2 kJmoH. Attempts to estimate an enthalpy of formation for A-methyldodecanamide reveals a paucity of data to work with, primarily for unsubstituted and A-methylamides . There is much enthalpy of formation data for w-alkyl carboxylic acids, including dodecanoic acid. The methylene increment... 

Alkyl Diethyl malonate a-Alkylated Carboxylic acid... 

Diesters of dibutyldiethanolammonium halides and 2 mol alkyl carboxylic acid (optimum 12-14 carbons)... 

Figure 4.2 shows the results obtained in rat colon with sodium lauryl sulfate and phenyl-alkyl-carboxylic acids. While correlations between ka and Pin the absence of surfactants are hyperbolic, correlations in the presence of CMC of synthetic surfactants are always potential with a rather low slope. Below or at the CMC [27, 28] the... 

An example of the correlations obtained in small intestine in the absence and in the presence of tetradecyltrimethylamonium bromide (TTAB) at 0.0125% (CMC) is represented in Fig. 4.4 [26]. As can be seen, the effect of each surfactant concentration is quite significant. But, a natural surfactant such as sodium taurocholate did not produce any significant change in the absorption rate constants of a series of phenyl-alkyl carboxylic acids at its CMC and it exerted an almost negligible solubilization effect at a supramicellar concentration [23]. 

Fig. 13.42. Helmchen synthesis of enantiomerically pure a-alkylated carboxylic acids. The deprotonation of the propionic acid ester results in the "f "-enolate in the solvent THF and in the "Z"-enoLate in the solvent mixture THF/HHPA. In these projections, both enolates react preferentially from the front. The "f" -enolate results in a 97 3 mixture of 5- and fi-configured a-benzyl-propionic acid esters (X marks the chiral alkoxide group), while the "Z"-enolate results in a 5 95 mixture. Chromatographic separation and reduction of the C(=0)—Xc groups afford alcohol B with 100% ee from the " "-enolate and alcohol ent-B with 100% ee from the "Z"-enolate.

Fig. 13.43. Evans synthesis of enantiomerically pure a-alkylated carboxylic acids.

The alkylations of the oxazolidinone-containing amide enolate of Figure 13.43 occur with diastereoselectivities of 93 7 and > 99 1, respectively. The hydrogen peroxide-accelerated alkaline hydrolysis of these compounds occurs with complete retention of the previously established configuration at the a-stereocenter. To date, the Evans synthesis offers the most versatile access to enantiomerically pure a-alkylated carboxylic acids. 

Oxime esters of aryl and alkyl carboxylic acids are apparently better substrates. These compounds decompose under irradiation, in presence of CC14, to yield aryl and alkyl chlorides in high yields (equation 70)597 ... 

In a similar process, a-haloalkyl carbonates have been used to alkylate carboxylic acid-containing pharmaceuticals through reaction as the carboxylate (equation 47). The aim of this reaction is to produce a prodrug which has modified solubility and absorbtion properties which may enhance its pharmaceutical properties373,375,376. 

Fig. 10.38. Evans synthesis of enantiomerically pure a-alkylated carboxylic acids. The amides are derived from oxazolidinones and yield Z -enolates with high stereoselectivity. The alkylating agent attacks in both cases from the side that is opposite to the side of the substituent highlighted in red.

Esters, as functional groups, are simply oxygen-alkylated carboxylic acids (see Fig. 1.3). As such, we cannot remove a proton from the oxygen as we are able to do with carboxylic acids. However, as shown in Scheme 2.9, the proton in the position a (adjacent) to the ester... 

On the other hand, the progress of wet-processes as preparative techniques of metal oxide films has been remarkable. The so-called soft solution process that provides oxide layers by means of electrochemical oxidation of a metal surface is expanding as a synthetic method of various mixed metal oxides with controlled thickness [2], The two-dimensional (2D) sol-gel process based on the hydrolysis of metal alkoxides at the air/water interface has been reported as a preparative technique of ultrathin oxide films (Fig. 6.1a) [3]. It is also known that LB films of metal complexes of long-chain alkyl carboxylic acid can be converted to metal oxide films after removal of organic component by oxygen plasma [4] and UV-ozone treatments (Fig. 6.1b) [5]. Preparation of metal oxide... 

Straight-chain alkyl carboxylic acids derived from petroleum that also have a terminal cyclohexyl or cyclopentyl group are known as naphthenic acids. They form complexes, presumably polymeric, with many transition metals, and these compounds are freely soluble in petroleum. Copper naphthenates are used as fungicides, aluminum naphthenate was used as a gelling agent in napalm, and cobalt naphthenates are used in paints. 

Four recent examples of universal linkers/supports, in which the first nucleoside is anchored onto the preformed linker-support construct, are shown in Fig. 2.14. The disulfide linker 2.33 has been used to prepare terminal 3 -phosphate ONs (94, 95) through cleavage with a solution of ammonia in dithiothreitol. The photolabile linker 2.34 (96) is used to prepare 3 -alkyl carboxylic acids. The allyl-based linker 2.35 (97) is used to prepare free 3 -OH ONs by cleavage with Pd(0) and treatment with an aqueous buffer at pH 10. The linker 2.36 (98) differs from those discussed so far in... 

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