Carboxylic acids and aldehydes

On the other hand, following the same sequences from the differently protected serine-derived nitrone 168, through the formation of hydroxylamines 169, C2 epimers of carboxylic acid and aldehydes are obtained, i.e., (2S,3R)-170 and (2S,3R)-171. Moreover, the syn adducts 164 were exclusively obtained in the addition of Grignard reagents to the nitrone 163, whereas the same reactions on nitrone 168 occurred with a partial loss of diastereoselectivity [80]. Q, j6-Diamino acids (2R,3S)- and (2R,3R)-167 can also be prepared from the a-amino hydroxylamines 164 and 169 by reduction, deprotection and oxidation steps. The diastereoselective addition of acetylide anion to N,N-dibenzyl L-serine phenyhmine has been also described [81]. 

Zammatteo et al. (2000) Preparation of carboxylic acid and aldehyde slides... 

Preparahon of functional carboxylic acid and aldehyde groups see below. 

Azine approach. 8,8a-Dihydro-l-oxo-l//,3//-oxazolo[4,3-c][l,4]thiazines (265) are available from the corresponding l,4-thiazine-3-carboxylic acids and aldehydes or ketones 2,2-dimethoxypropane with acid catalysis yields the 3,3-dimethyl derivative (265 R=Me), and acetaldehyde with a water absorbent yields the monomethyl derivative as a diastereoisomeric mixture (76JCS(P1)584>. 

The carboxylic acid and aldehyde functional groups are located at an end of the molecule, whereas ketones and esters have their functional group located in the interior of the molecules. 

Partial oxidation usually leads to the formation of innocuous and biodegradable low molecular weight products, such as carboxylic acids and aldehydes... 

Heteropoly acids can also act as oxidation catalysts both in the vapor and liquid phase. In the vapor phase they are effective dehydrogenation catalysts for saturated carboxylic acids and aldehydes readily converting isobutyric acid to methacrylic acid (Eqn. 10.19). Methacrylic acid is produced in 70% selectivity at 72% conversion over (NH4)3PMoi204q at 260°C. This reaction takes place only when there is a substituent a to the carbonyl group of the reactant. 

When the vinyllithium intermediate (190) is treated with water, the procedure provides a useful synthetic method for the conversion of ketones to alkenes (Scheme 79). The method is illustrated by the conversions of the tosylhydrazones of phenyl isopropyl ketone (194) and dipropyl ketone (195) to the alkenes (196) and (197), respectively (Scheme 79). In this method, experiments have demonstrated that the hydrogen is derived from the water, as indicated in Scheme 79, and thatTMEDA is an excellent solvent. The vinyllithium intermediate (190) may be trapped by other electrophiles thus, with carbon dioxide and DMF, the reaction affords ,[i-unsaturated carboxylic acids and aldehydes like (198) and (199) (Scheme 80). 

Polyvinylpyrrolidone (PVP) is suited for the preparation of samples that contain humic acids, lignins, tannins, and azo dyes. In addition, PVP exhibits a high selectivity for phenolic compounds as well as for aromatic carboxylic acids and aldehydes. PVP is stable to all common HPLC solvents and is stable in the pH range between 1 and 10. 

As was observed with the Kumada and Negishi reactions, the reactions conditions required to conduct the cross-coupling reaction may not be compatible with a wide variety of functional groups. The mild nature of the Suzuki reaction has been demonstrated by the types of functional groups that can be retained unprotected or via methods to modulate the reaction [65]. The coupling of 184 and 185 to generate 186 provided evidence that carboxylic acids and aldehydes are compatible with the Suzuki reaction. 

Besides acting as an electron scavenger, the precise role of O2 has been elusive for some time and continues to be a subject of some debate. In several studies on the photocatalysed oxidation of aliphatic hydrocarbons, alcohols, ketones, carboxylic acids and aldehydes, Heller (1995) concluded that molecular O2, and not the photogenerated hole or OH radical, is the primary oxidising agent. As evidence, data were given that photooxidation of n-octane films on water produced only traces of octanols. 

This reaction was done with a variety of substituted aromatic and aUphalic carboxylic acids and aldehydes. Unlike the aromatic aldehydes that produced the corresponding products in high purity and good yields, reactions with aliphatic aldehydes produced several unidentified substances together with the desired a-(acyloxy)carboxamide products. In the case of ketones, cyclohexanone was successfully included into this 3-CC process and gave the corresponding products in reasonable yield, but attempts to use acetophenone as the carbonyl substrate failed. The inactivity of the acetophenone in this reaction may be due to the steric effect of the relatively bulky phenyl group. 

Spectroscopic studies of the interaction between ozone and organic molecules on catafyst sur ces have been very rare. Mariey et aL [S] rq>orted a Fourier transform infrared (FTIR) study of ozone interaction with phenol adsorbed on rilica and ceiia. Ozone was found to be reactive toward phenol and carboxylic acids and aldehydes were detected as posable intermediates. However, the study was carried out from 77 to 220 K, which is far from... 

Oxygen was measured only in the asphaltenes due to sample size limitations. Combined results indicated that over 50% of the oxygen was liberated during these reactions as gaseous species and this is in good agreement with recently published work of Moschopedis et al (5) suggesting the presence of carboxylic acid and aldehyde functionality. 

Wynder, E.L., D.A. Goodman, and D. Hoffmaim CUiatoxic components in cigarette smoke. II. Carboxylic acids and aldehydes Cancer 18 (1965) 505-509. Wynder, E.L., D.A. Goodman, and D. Hoffmaim CUiatoxic components in cigarette smoke. IB. in vitro comparison of different smoke components Cancer 18 (1965) 1652-1658. 

Most tungstoenzymes isolated so far have been from obligate anaerobes that are also thermophilic to a greater or lesser extent. Moreover, the enzymes have similar catalytic properties. They all catalyze a redox reaction involving conversions at the level of carboxylic acids and aldehydes (with the exception of AH). However, their physiological roles are distinctly different. 

This review covers the catalytic literature on condensation reactions to form ketones, by various routes. The focus is on newer developments from the past 15 years, although some older references are included to put the new work in context. Decarboxylative condensations of carboxylic acids and aldehydes, multistep aldol transformations, and condensations based on other functional groups such as boronic acids are considered. The composition of successful catalysts and the important process considerations are discussed. The treatment excludes enantioselective aldehyde and ketone additions requiring stoichiometric amounts of enol silyl ethers (Mukaiyama reaction) or other silyl enolates, and aldol condensations catalyzed by enzymes (aldolases) or catalytic antibodies with aldolase activity. It also excludes condensations catalyzed at ambient conditions or below by aqueous base. Recent reviews on these topics are those of Machajewski and Wong, Shibasaki and Sasai, and Lawrence. " The enzymatic condensations produce mainly polyhydroxyketones. The Mukaiyama and similar reactions require a Lewis acid or Lewis base as catalyst, and the protecting silyl ether or other group must be subsequently removed. However, in some recent work the silane concentrations have been reduced to catalytic amounts (or even zero) this work is discussed. 

Generation of the carboxylic acid and aldehyde at the C-13 position of the salvinorin A scaffold has granted access to a variety of chemical methods for the development of salvinorin A analogs with a C-13 carbonyl moiety. From carboxylic acid 125, alcohols and ethers at C-13 have been synthesized [44]. The primary alcohol at C-13 (127) was produced in 46% yield by reducing carboxylic acid 125 using BHs THF (Scheme 21). Alcohol 127 was then alkylated using alkyl iodides in the presence of Ag20 to afford alkyl ethers (128 and 129) in 12-15% yield. The primary alcohol was also acetylated (130) in 11% yield with acetic anhydride and EtsN. 

Isotetronic acids were readily assembled through an organocatalyzed domino aldol-lactonization reaction starting from a-keto carboxylic acids and aldehydes [5]. As chiral organocatalyst, the proline-derived benzimidazol pyrrolidine 8 was employed, which proved superior to proUne itself Electron-poor aldehydes were both more reactive and selective. Thus, as a typical example, pyruvate was converted into isotetronic acid 10 in 77% yield and 83% ee upon treatment with para-nitrobenzyldehyde (9) and 10mol% 8 (Scheme 8.3). 

Chromium trioxidelsulfuric acid Carboxylic acids and aldehydes from prim, alcohols... 

In organic analysis, most of the time the determinations involving dichromate ions are back titrations. The dichromate in excess is determined by indirect iodometry. Several organic compounds can be determined by chromimetry, including ethylenics, alcohols, carboxylic acids, and aldehydes. The reaction products are usually water and carbon dioxide. Ethanol gives acetic acid. This reaction is used to determine the alcohol level in blood. 

The intermediate from this initial attack on a double bond is an ozonide as shown generally in Figure 1. Due to the high oxygen content of this intermediate, it is not stable and spontaneously decomposes to a mixture of carbonyl compounds. Various carboxylic acid and aldehyde derivatives of vegetable oils have been prepared in the past by such ozonolysis reactions and this process was commercialized by Emery Industries to manufacture azelaic and pelargonic acids from oleic acid. ... 

The extension of the NMR methods for the assignment of the configuration of secondary alcohols described previously to other substrates is particularly appealing, because systems such as primary alcohols with the chiral center in the position yS to the OH group, are frequently found in nature in chiral forms or are obtained by a reduction of the carboxylic acids and aldehydes. 

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