Glyoxylate isolation

J. Jurczak, A. Golebiowski, A. Rahm, High-pressure [4+2] cycloaddition of l-methoxya-3-trialkylsrlyloxybuta-l,3-dienes to butyl glyoxylate. Isolation of primary cycloadducts. Tetrahedron Lett. 27 (1986) 853-856. 

In a study of the nitrosation of camphor-3-glyoxylic acid (89), Chorley and Lapworth isolated a compound whose structure (90) has recently been clarified by Hatfield and Huntsman. Decarboxylation and ring expansion occur and the reaction is rationalized in the sequence 89 90. The buttressing effect of a methyl group on... 

Chiral boron(III) complexes can catalyze the cycloaddition reaction of glyoxy-lates with Danishefsky s diene (Scheme 4.18) [27]. Two classes of chiral boron catalyst were tested, the / -amino alcohol-derived complex 18 and bis-sulfonamide complexes. The former catalyst gave the best results for the reaction of methyl glyoxylate 4b with diene 2a the cycloaddition product 6b was isolated in 69% yield and 94% ee, while the chiral bis-sulfonamide boron complex resulted in only... 

Hesse and Mix (29) oxidized a relatively concentrated solution of triose reductone using limited amounts of free periodic acid. In these conditions, the iodic acid formed by the initial reduction of periodic acid could be further reduced and the reduction product could then, in turn, react with the remaining periodic acid and liberate iodine. Thus glyoxylic acid could be isolated from the oxidation mixture, as no periodate was available for its oxidation. 

C-Disaccharide analogs of trehalose were recently [20c] prepared by using as a key step an aqueous Diels-Alder reaction between the sodium salt of glyoxylic acid and the water soluble homochiral glucopyranosil-l,3-pentadiene 19 (Equation 6.1). A mixture of four diastereoisomers in a 41 24 21 14 proportion was obtained after esterification with methanol and acetylation. The main diaster-eoisomer 20 was isolated and characterized as benzoyl-derivative. 

Chloro-l,2-benzenediamine (137) and glyoxylic acid gave a mixture of 6-chloro- (138) and 7-chloro-2(l//)-quinoxalinone (139) from which only 6-isomer could be isolated in a pure state (OHCCO2H, H20-Me0H, 20°C, 24h 37%). ... 

Similar transformations have been performed with Danishefsky s diene and glyoxylate esters [85] catalyzed by bis (oxazoHne)-metal complexes to afford the hetero Diels-Alder product in 70% isolated yield and up to 72% ee. Jorgensen [86,87] reported a highly enantioselective, catalytic hetero Diels-Alder reaction of ketones and similar chiral copper(II) complexes leading to enantiomeric excesses up to 99% (Scheme 31, reaction 2). They also described [88] a highly diastereo- and enantioselective catalytic hetero Diels-Alder reaction of /I, y-imsaturated a-ketoesters with electron-rich alkenes... 

Li et al.39 reported the hetero Diels-Alder reaction of alkyl-3-(t-butyldimethylsilyl) oxy-1,3-butadiene 95 with ethyl glyoxylate 96 in the presence of a salen-Co(II) catalyst 94 (2 mol%). Product 97 was obtained in 75% isolated yield with an endo. exo ratio >99 1. The enantiomeric excess of the endo-iorm was up to 52% (Scheme 5-30). 

Although the present procedure illustrates the formation of the diazoacetic ester without isolation of the intermediate ester of glyoxylic acid />-toluenesulfonylhydrazone, the two geometric isomers of this hydrazone can be isolated if only one molar equivalent of triethylamine is used in the reaction of the acid chloride with the alcohol. The extremely mild conditions required for the further conversion of these hydrazones to the diazo esters should be noted. Other methods for decomposing arylsulfonyl-hydrazones to form diazocarbonyl compounds have included aqueous sodium hydroxide, sodium hydride in dimethoxyethane at 60°, and aluminum oxide in methylene chloride or ethyl acetate." Although the latter method competes in mildness and convenience with the procedure described here, it was found not to be applicable to the preparation of aliphatic diazoesters such as ethyl 2-diazopropionate. Hence the conditions used in the present procedure may offer a useful complement to the last-mentioned method when the appropriate arylsulfonylhydrazone is available. 

CASRN 94-74-6 molecular formula CgffgClOs FW 200.63 Biological. Cell-free extracts isolated from Pseudomonas sp. in a basal salt medium degraded MCPA to 4-chloro-o cresol and glyoxylic acid (Gamar and Gaunt, 1971). 

A benzotriazole-assisted synthesis of ethyl 5-aminoimidazo[2,l-h]thia-zole-6-carboxylate 65 has been developed (96TL1787). Traces of compound 63 were isolated from 2-aminothiazole 23 using benzotriazole and freshly distilled ethyl glyoxylate in benzene, whereas by application of a-benzotria-zolyl-a-morpholino acetate with methyl iodide in THF, 63 was isolated in 40% yield. Subsequent treatment of 63 with potassium cyanide in ethanol at rt involves substitution of the benzotriazole moiety. Intramolecular cycli-zation of 64 yields 65, albeit in 10% yield. a-Ketoester 66 is also obtained (Scheme 3). 

Shortly before Hopkins and Cole isolated tryptophane, they studied the Adamkiewicz reaction—the production of a violet colour when concentrated sulphuric acid is added to a protein dissolved in glacial acetic acid—and found that it was caused by the presence of glyoxylic acid in the glacial acetic acid, from which it arose by the action of sunlight. On applying the glyoxylic reaction to tryptophane a very intense colour was produced, and hence the presence of tryptophane in the protein molecule is the cause of this reaction. 

EXTENSIONS AND COMMENTARY N-Methyltryptamine (monomethyltryptamine, NMT) is an alkaloid that has been found in the bark, shoots and leaves of several species of Virola, Acacia and Mimosa. However, the major snuffs associated with these plant have been shown to also contain 5-MeO-DMT and are discussed there. NMT has been synthesized in a number of ways. One can react 3-(2-bromoethyl)indole with methylamine. NMT can be isolated as the benzoyl derivative from the methylation of tryptamine with methyl iodide followed by reaction with benzoyl chloride, with the hydrolysis of this amide with alcoholic KOH. It can also be synthesized from indole with oxalyl chloride, with the resulting glyoxyl chloride reacting with methylamine in ether to give indol-3-yl N-methylglyoxalylamide (mp 223-224 °C from IPA) which is obtained in a 68% yield, which is reduced to NMT to give the amine hydrochloride (mp 175-177 °C from ) in a 75% yield. The most simple and direct synthesis is the formamide reduction given above. 

With aromatic and heteroaromatic aldehydes,193 4-oxo-6,7,8,9-tetra-hydro-4T/-pyrido[l,2-a]pyrimidines yielded the 9-arylmethylene derivatives,133,266 whereas with glyoxylic acid the 9-carboxymethylene derivative was formed.266,267 The primary addition product (237) could be isolated from the reaction mixture of ethyl 6-methyl-4-oxo-6,7,8,9-tetrahydro-4//-pyrido[l,2-a]pyrimidine-3-carboxylate and benzaldehyde. On dehydration the addition product (237) gave the 9-benzylidene compound.266 The 9-carboxymethylene derivatives may be transformed by catalytic hydrogenation to the 9-acetic acids, which can be esterified.266,267... 

The stereochemical outcome of the aldol addition reactions to pyruvate and glyoxylates catalyzed by Sn(II) were complementary to the Cu(II)-catalyzed process, giving the anti stereoisomers. Thus, aldol adducts were isolated as mixtures of 10 90-1 99 syn anti diastereom-ers in 92-99% ee. 

Addition of nucleophiles to electrophilic glycine templates has served as an excellent means of synthesis of a-amino acid derivatives [2c, 4—6]. In particular, imines derived from a-ethyl glyoxylate are excellent electrophiles for stereoselective construction of optically active molecules [32], This research and retrosyn-thetic analysis led us to believe that amine-catalyzed asymmetric Mannich-type additions of unmodified ketones to glyoxylate derived imines would be an attractive route for synthesis of y-keto-ce-amino acid derivatives [33], Initially, L-proline-catalyzed direct asymmetric Mannich reaction with acetone and N-PMP-protected a-ethyl glyoxylate was examined in different solvents. The Mannich-type reaction was effective in all solvents tested and the corresponding amino acid derivative was isolated in excellent yield and enantioselectivity (ee >95 %). Direct asymmetric Mannich-type additions with other ketones afford Mannich adducts in good yield and excellent regio-, diastereo- and enantioselectivity (Eq. 8). 

S)-Proline also catalyzed the Mannich-type reactions of unmodified aldehydes and N-PMP-protected imines to afford the corresponding enantiomerically enriched / -aminoaldehydes at 4 °C (Table 2.13) [71b]. The products were isolated after reduction with NaBH4, though oxidation to the / -amino acid is also possible. These reactions also provided the syn-isomer as the major diastereomer with high enantioselectivities, and proceeded well in other solvents (e.g., dioxane, THF, Et20). In the reaction of propionaldehyde and the N-PMP-imine of 4-nitrobenzaldehyde in DMF, the addition of water (up to 20%, v/v) did not affect the enantioselectivity. Similar results were obtained for the (S)-proline-catalyzed Mannich-type reactions with the glyoxylate imine where water did not reduce enantioselectivity [71b]. However, the enantioselectivity of the reaction of propionaldehyde and the N-PMP-imine of benzaldehyde in DMF was decreased by the addition of water or MeOH [71b]. 

An excellent simple and induced selectivity could be obtained by Mulzer and his group [92] in the cycloaddition of 2-trimethylsilyl-oxy-l,3-pentadiene 2-31 and (lR,2S,5R)-8-phenylmenthyl glyoxylate 2-32 [93] in the presence of 0.2 equivalents of anhydrous MgBr2 in THF at 0 °C. After acidic workup the ketone 2-33 was isolated as a single diastereomer (>98%), which was then used for synthesis of the C-26-C-32 tetrahydropyran moiety of swinholide. In contrast,... 

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