Alkoxy Moiety Research Articles

Reductive carbonylation of carboxylic esters in the presence of homogeneous ruthenium-cobalt systems. Homologation of the alkoxy moiety

Homogeneous Co-Ru systems in the presence of an iodide promotor can catalyse homologation of the alkoxy moiety of carboxylic esters. For low molecular weight esters, the ruthenium has a synergistic effect. The mechanism is thought to parallel that of the mechanism generally applying to the homologation of alcohols, and is believed to involve at least in part an olefinic intermediate originating from the alkyl moiety and undergoing hydroformylation into the higher alcohol. Subsequent esterification produces the expected ester. The best yields of the higher ester are obtained when elemental iodine is used along with an ionic iodide.

Novel aryl oxalate esters for peroxyoxalate chemiluminescence reactions

Six oxalate esters of 2-nitro-4-alkoxycarbonylphenol and 2-alkoxycarbonyl-4-nitrophenol were synthesised for use in the peroxyoxalate chemiluminescence reactions that take place via several steps with 4-hydroxy-3-nitrobenzoic acid and 5-nitrosalicylic acid as starting materials, respectively. The addition of ethylene glycol to the alkoxy moiety enhanced the solubility in solvents such as acetone, acetonitrile and ethyl acetate. When reacted with hydrogen peroxide in the presence of a fluorescent compound, perylene, they gave similar chemiluminescence reaction curves to those of DNPO [bis(2,4-dinitrophenyl) oxalate] and TCPO [bis(2,4,6-trichlorophenyl) oxalate]. Among them, bis[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl] oxalate was found to be the best for the high-sensitivity detection of both hydrogen peroxide and fluorescent compounds using the peroxyoxalate chemiluminescence reaction because of its extreme solubility in solvents such as acetone (767 mM) and acetonitrile (1010 mM).

The regioselective chemistry of alkoxyxenon fluoride

Xenon difluoride reacts with methanol to form the unstable reactive species methoxyxenon fluoride ( 1 ). In the absence of unsaturated hydrocarbons, this specie quantitatively disproportionates to formaldehyde and hydrogen fluoride; however, in the presence of alkene substrates a competitive methoxyfluorination reaction results. During methoxyfluorination, the highly reactive intermediate ( 1 ) displays a novel ambivalent addition character depending upon whether catalysis is accomplished by protonic acids (H 2SO 4 & HF generated in-situ ) or Lewis acid species (BF 3 & BF 3 etherate). Catalysis with protonic acids produces an apparent fluorine electrophilic intermediate ( 2 ) where fluorine adds first and results in Markownikoff fluoromethoxy products predominating. Reaction in the presence of Lewis acids provides a positive oxygen electrophile as intermediate ( 3 ) where the methoxy group adds first and produces ▪ mainly anti -Markownikoff fluoromethoxy products. The reaction mechanism involving species 1 , 2 , and 3 were studied by using five alkenes with varying structural features; in the case of the very electron rich alkene dihydropyran, reaction with XeF 2 occurred before 1 could form. Current mechanistic studies of this alkoxyfluorination reaction involve varying the alcoholic substrate with electron-donating and electron-withdrawing alkoxy moieties.

Activity of ruthenium/iodine catalysts for the carbonylation of esters to give carboxylic acids

Abstract Homogeneous ruthenium/iodide systems under a pressure of carbon monoxide effectively catalyze the isomerization of methyl formate to acetic acid with yields in the range of 70%. If alkyl acetates are treated with CO/H 2 , the dominant process is the carbonylation of the alkoxy moiety rather than the homologation of the acetyl or alkoxy moieties; e.g. n-butyl acetate is converted mainly into valeric acid and its derivatives, along with acetic acid and butane. Only in the case of methyl acetate is homologation of the alkoxy moiety, to give ethyl acetate along with acetic acid, the major process. This duality of behaviour can be rationalized in terms of η 2 -acetyl intermediates, which can be hydrogenated to ethanol rather than hydrolyzed to acetic acid. Ester carbonylation is shown to be fast compared with alcohol carbonylation or acid homologation; esters are probably intermediates in the last process.

Oxygen‐17 nuclear magnetic resonance spectral investigation of 3‐alkoxy‐trans‐3,4‐disubstituted‐thiolane 1,1‐dioxides and related compounds

AbstractThe 17O NMR spectra of 3‐alkoxythiolane 1,1‐dioxides indicate that the sulfonyl oxygens are diastereotopic but their chemical shift differences are essentially independent of the structure of the alkyl group in the alkoxy moiety. Eu(fod)3 enhances the 17O chemical shift differences between the diastereotopic sulfonyl oxygens in 3‐isopropoxythiolane 1,1‐dioxide and shifts both oxygens upfield. α,β‐Unsaturation deshields the sulfonyl oxygens in both five‐ and six‐membered rings.

Hauts rendements optiques obtenus dans la synthese d′α-alkylα-hydroxyesters par reaction d'alkoxytrialkylaluminates encombres avec le phenylglyoxalate de menthyle.

Enantiomeric purities in alkylation of (+) and (−) menthyl esters of phenylglyoxilic acid by complexes derived from AlEt 3 and the lithium salts of (+) and racemic Darvon alcohol are depending upon the only stereochemistry of the menthyl group in ester. These results suggest that the observed stereoselectivity is to be related to the bulkiness of the organometallic reagent, which overcomes the asymetric induction due to the chiral center of the alkoxy moiety. Accordingly, use of complexes from AlEt 3 and non chiral alcohols of increasing sizes leads to increasing stereoselectivity.

Studies on antihyperlipidemic agents. III. Synthesis and biological activities of 2-chloro-3-arylpropionic acids containing a quarternary carbon atom.

A series of 2-chloro-3-(4-alkoxyphenyl)propionic acids containing a quarternary carbon atom in the alkoxy moiety was prepared and the hypolipidemic and hypoglycemic activities were evaluated. Of the 18 compounds synthesized, ethyl 2-chloro-3-[4-(2-methyl-2-phenylpropyloxy)phenyl]propionate (1) was the best with respect to biological activity and toxicity. Its functional derivatives and optically resolved enantiomers were also prepared. Structure-activity relationships are discussed briefly.

Thermolytic Pathway to Allyl Arenoates

Abstract Application of Tishchenko reaction to the direct synthesis of esters from aldehydes bears the shortcomings in being wasteful on part of aldehydes and compulsory predestination of the alkoxy moieties. More controllable routes are those via carboxylic acids and acetals. Several reagents have proven effective for oxidation of the latter, e.g., N-bromosuccinimide,1 peracids2, and ozone.3

Mass spectrometric analysis of mono‐ and dialkyl ethers of diols

Mass spectra of homologous series of long chain mono- and dialkyl ethers of ethanediol and propanediols were measured and general patterns of fragmentation were established. Both classes of diol lipids produce ions which are characteristic for the alkoxy moieties as well as ions which are typical of the constituent short chain diols. Prominent ions are formed by cleavages α and β to the ether oxygen and by rearrangement of one or two hydrogens and concurrent fission. High resolution mass spectrometry and deuterium labeling techniques were used to verify the composition of ions and to substantiate fragmentation mechanisms.

Metabolism of unusual lipids in the rat. I. Formation of unsaturated alkyl and alk-1-enyl chains from orally administered alcohols

cis-9-Octadecenyl alcohol (oleyl alcohol), orally administered, increased the relative concentration of 18:1 alkyl and alk-1-enyl moieties in alkoxylipids of the small intestine of rats. Trioleoyl glycerol (triolein) failed to produce the same effect. When a diunsaturated alcohol, cis,cis-9,12-octadecadienyl alcohol (linoleyl alcohol) was fed to rats, diunsaturated alkyl and alk-1-enyl moieties were found in the ionic alkoxylipids of the small intestine. These polyunsaturated alkoxy moieties could not be detected in the same tissue of control animals or of rats fed trilinoleoyl glycerol (trilinolein). It is concluded that, in the rat, long-chain alcohols, including polyunsaturated ones, are more direct precursors of both alkyl and alk-1-enyl moieties than are fatty acids or their esters. Alkoxylipids containing polyunsaturated alkyl and alk-1-enyl moieties are not normally formed in the small intestine and other organs of the rat because precursors, i.e. polyunsaturated alcohols are not present in these tissues. A portion of orally administered mono- and diunsaturated alcohols is esterified to form wax esters.