Carbonyl carboxaldehyde

In comparison to 1 and 2, the SERS spectra of 3-pyridine-carboxaldehyde (3) are relatively featureless (8). The spectra are dominated by the symmetrical ring-breathing mode at 1030 cm 1 but the features associated with the unprotonated species (about 1600 cm ) and the protonated species (about 1640 cm 1) are definitely present along with a weak carbonyl band at about 1710 cm . The variation in the relative population of protonated species is as expected (Figure 5) though a detailed analysis reveals some surprises. As can be seen in Figure 5, about equal intensities of the 1600 and 1640 cm bands are obtained at pH = 3.86, near the pKa (3.73 (9)). However, the band associated with the unprotonated pyridine persists at pH = 1.3, where less than 1J of the solution species remains unprotonated. 

The aziridine 101 derived from pyrrole-2-carboxaldehyde was found to undergo a further unusual transformation when treated with trifluoroacetic acid (TFA) at room temperature, giving the 5//-pyrrolo[l,2-r ]imidazole 102 in good yield. The cyclization is initiated by protonation of the carbonyl group (Scheme 10) <2000TL4991>. 

S)-(-)-CITRONELLOL from geraniol. An asymmetrically catalyzed Diels-Alder reaction is used to prepare (1 R)-1,3,4-TRIMETHYL-3-C YCLOHEXENE-1 -CARBOXALDEHYDE with an (acyloxy)borane complex derived from L-(+)-tartaric acid as the catalyst. A high-yield procedure for the rearrangement of epoxides to carbonyl compounds catalyzed by METHYLALUMINUM BIS(4-BROMO-2,6-DI-tert-BUTYLPHENOXIDE) is demonstrated with a preparation of DIPHENYL-ACETALDEHYDE from stilbene oxide. A palladium/copper catalyst system is used to prepare (Z)-2-BROMO-5-(TRIMETHYLSILYL)-2-PENTEN-4-YNOIC ACID ETHYL ESTER. The coupling of vinyl and aryl halides with acetylenes is a powerful carbon-carbon bond-forming reaction, particularly valuable for the construction of such enyne systems. 

A -tritylaziridine-2-(5)-carboxaldehyde. The application of a novel, sequential, trans-acetalation oxonium ene cyclization has delivered a stereoselective synthesis of the C-aromatic taxane skeleton, and a combinatorial sequence of the regioselective propiolate-ene, catalytic enantioselective epoxidation and carbonyl-ene cyclization reactions has been used to complete the synthesis of the A-ring of a vitamin D hybrid analogue. 

Mixed donor ligands. The complex [FeL3]Cl3 (L = acetylhydrazine) contains the ligand in its bidentate form, bonded via the carbonyl and primary amino-groups.Pyridine-2-carboxaldehyde and l,l,l-tris(aminoethyl)ethane react with Fe" via a template reaction to form [Fejlpyljltame) ], in which three molecules of carboxaldehyde have condensed with one molecule of triamine to produce (pyljltame). MeC(CH2N=CH-oc-py)3 the complex cation is octahedral. The complexes [FeL ] (L = l,10-phenanthroline-2-carboxamide, n = 1 or 2) have been isolated they are both six-co-ordinate. Very weak d-d bands have been identified in the spectra of complexes of ot-picolinic acid and quinaldic acid with Fe". ... 

Reactions of carbonyl compounds such as pyridine 2-carboxaldehyde, glyoxal, biacetyl, or benzil with 2-aminothiophenol on an Fe + template give benzothiazolinate (198) complexes. The complex from pyridine 2-carboxaldehyde, for example, was formulated, on the basis of NMR and Mossbauer spectroscopy and of analysis (C, H, N, and Fe) as the bis-(A,iS)-ligand-bis-aqua complexes of (199), an isomeric form in equilibrium with (198). However as they are diamagnetic it seems more likely that they are [Fe(199)2] 2H20, containing terdentate (N,N,S) (199), than the proposed [Fe(199)2(H20)2]. 

The insertion of carbon monoxide into azolylpalladium complexes proceeds readily and in most cases leads to the formation of carboxylic acid derivatives or ketones. In a modified version of the carbonylation 3-bromothiophene was reacted with carbon monoxide in the presence of sodium formate. This reagents converts the intermediate acylpalladium formate complex, through the release of carbon dioxide into the acylpalladium hydride (c.f 7.47.), which in turn releases thiophene carboxaldehyde as the sole product (6.62.),92 If sodium formate was replaced... 

The carbonyl and 2,3-double bond of pyran-4-ones and their monobenzo derivatives are reducible and therefore attempts to reduce functional groups such as carboxaldehyde, carboxylate ester, carboxylic acid chloride or nitrile need careful selection of reagents. The reducibility of a particular group varies with the nature of other substituents present and it is not possible to generalize about the conditions required for each reaction. 

A considerable number of electrophiles were used, and the dithiane route found great utility for the syntheses of simple monofunctional compounds as well as for polyfunctional molecules, for which the dithiane moiety affords an invaluable temporary protection of a future carbonyl group. Some experimental procedures published in Organic Syntheses — cyclobutanone [277] and 3-hydroxy-l-cyclohexene-l-carboxaldehyde [278] — are illustrative. A similar route to aldehydes [279] makes use of sym-trithiane as a formyl anion equivalent. 

Recently, Indian workers (61) reported that 2-naphthylmethylene triphenylarsorane reacted with substituted benzaldehydes to give the corresponding epoxides exclusively, whereas l-bromo-2-naphthylmethylene triphenylarsorane reacted with substituted benzaldehydes to give only olefins. In no case were both olefin and epoxide isolated and in all cases only fram-epoxides or trans-olefins were detected. It has also been reported that reaction of indole-3-carboxaldehyde with semistabilized ar-sonium ylides followed only the trans -carbonyl olefination (91). 

A historic method for 1,2,4-oxathiazolidine synthesis is based on 1,3-cycloaddition reactions, for example, addition of carbonyl compounds across the S-C=N groups of 5-imino-l,2,3,4-thiatriazolines <1996CHEC-II(4)453>. The thermally induced conversion of 677-1,3,5-oxathiazine A-oxides 119 in refluxing benzene results in 1,2,4-oxathiazo-lines 20 in high yields by intramolecular cyclization with extrusion of carboxaldehydes (see Section 6.03.8.2). Oxidative cyclization of A-acylthioureas 114 and iV-acylthiocarbamates 115 by Br2 gives 1,2,4-oxathiazolium hydrobromides 43 and 38, respectively (see Section 6.03.8.1). 

Common names for simple aldehydes are frequently encountered. These common names are derived from the common names for the related carboxylic acid (see Section 12.4) by replacing the suffix -ic acid with the suffix -aldehyde. Thus, the aldehyde related to acetic acid is acetaldehyde. If the carbonyl group of an aldehyde is attached to a ring system, the compound can be named as a hydrocarbon with the suffix -carbaldehyde. (Some sources use -carboxaldehyde.)... 

S,5R)-3-tert-butoxy-carbonyl-2,2-dimethyl-4-phenyl-5-oxazolidine-carboxaldehyde (XIV)... 

Indole-3-carboxaldehydes gave the corresponding cyanohydrin silyl ethers 137 upon heating with trimethylsilyl cyanide in acetonitrile or DME. After subsequent oxidation with DDQ, good yields of the carbonyl nitriles 138 were obtained, also providing a mild new route for the parent system 138 (R1 = R2 = H). Further elaboration provided the imidates 139, which participated in a reaction with tryptophan esters to give moderate yields of the marine alkaloids rhopaladins A-D <02T2813>. 

The model predicts that the effect of the added carbonyl compound will be a function of its concentration. This was found for 1-adamantyl carboxaldehyde, for which induction was only 87 % ee with 0.1 equiv. and 82 % ee with 0.05 equiv. Malonates are the most effective additives reported and of these the most effective were those derived from the more bulky alcohols. This is dramatically illustrated by the effect of added diadamantyl malonate 259. On addition of 1.0 equiv. 259, asymmetric induction in the reaction is increased from 82 to 92 % ee at the same time as the reaction temperature is raised by 80 °C. The effect of malonate is even more dramatically illustrated by the graph in Fig. 2 for addition of 0.5 equiv. di-f-butyl malonate 258 to the reaction at -78 °C. The first data point taken in this reaction, at 25 % completion, reveals that the product 141 is more than 99 % optically pure and it remains so throughout the course of the reaction. 

---