Methyl glyoxalate

As the reaction sequence of Scheme 12-38 can be stopped at the stage of the oo-methylglyoxal phenylhydrazone (12.78), it is possible to synthesize asymmetrically substituted formazanes (12.80, Ar = Ar ) by reacting acetone with one equivalent of a diazonium ion ArNJ under acidic conditions and then coupling the co-methyl-glyoxal phenylhydrazone with Ar NJ in alkaline solution. 

Dihydro-2(l,3-dimethyluracil-5-yl)-l,3,4-oxadiazole was obtained in 53% yield by the [3+2] cycloaddition of diazomethane to the formyl group of l,3-dimethyl-5-formyluracil <1997T7045>. The reaction of l-acetyl-2-benzyl-hydrazine with methyl glyoxalate in toluene afforded an oxadiazolidine derivative <1996TL4323>. 

Mikami and co-workers16-19 have done extensive work for developing catalysts for the asymmetric carbonyl-ene reaction. Excellent enantioselectivites are accessible with the binol-titanium catalyst 17 (Equation (10)) for the condensation of 2-methyl butadiene (R1 = vinyl) and glyoxalates (binol = l,T-binaphthalene-2,2 -diol).16 The products were further manipulated toward the total synthesis of (i )-(-)-ipsdienol. The oxo-titanium species 18 also provides excellent enantioselectivity in the coupling of a-methyl styrene with methyl glyoxalate.17 Reasonable yields and good enantioselectivites are also obtained when the catalyst 19 is formed in situ from titanium isopropoxide and the binol and biphenol derivatives.18... 

Experiments with glyceraldehyde and dihydroxyacetone showed them to be fermentable, but results with methyl glyoxal were conflicting. With Lebedev juice no lactic acid was formed, but with top yeast Neuberg reported that lactic acid was detectable. In 1913 he and Kerb therefore proposed sugar was converted to methyl glyoxal from which pyruvic acid and ethanol were derived ... 

CH3COCHO - pyruvic acid -> CH3CHO + C02 methyl glyoxal carboxylase... 

Glyoxalase, the glutathione-dependent enzyme which catalyzed the conversion of methyl glyoxal to lactic acid, was isolated by Neuberg and by Dakin and Dudley. 

Methyl glyoxal was finally removed from the glycolytic pathway after Lohmann showed (1932) that dialysed muscle extracts, supplemented with Pj, ATP, NAD+, etc., converted glycogen to lactic acid. If glutathione was not present to reactivate glyoxalase, methyl glyoxal did not form lactic acid. 

Several nonhalogenated aldehydes were measured in the U.S. ICR effort, including formaldehyde, acetaldehyde, glyoxal, and methyl glyoxal [63]. These aldehydes are DBFs produced primarily by ozone, although both chlorine and chlorine dioxide... 

Terpenoid DBPs were investigated by Joll et al. [124] and Qi et al. [125]. The main ozonation product of 2-methylisobomeol was camphor, which was further oxidized to formaldehyde, acetaldehyde, propanal, buntanal, glyoxal, and methyl glyoxal [125]. Chlorination of p-carotene, retinol, p-ionone, and geranyl acetate resulted in the formation of THMs [124]. 

Aminomalonamide gave 47 in low yield when condensed with (4-pyridi-nyl)glyoxal [90H(31)2163]. Similar condensations are reported with methyl-glyoxal (49JA78) and of glycinamide with phenylglyoxal (78JHC665). 

This condensation with formaldehyde as well as with methyl glyoxal is confirmed by the formation of dimethylimidazole when ammonia acts upon glucose and acetaldehyde. 

The observation of the a-dicarbonyls glyoxal (CH(O)CHO), methyl-glyoxal (CH3C(0)CH0), and biacetyl (CH3C(0)C(0)CH3) in significant... 

On the other hand, upon reaction with methyl glyoxalate imines, an increase in bulk of the silyl moiety [i.e., PhMe2Si, Ph2MeSi, Ph3Si and (t-Bu)Ph2Si] in fi-(triorganosilyl)alkanoyl chlorides causes a moderate increase in the anti/syn ratio of the [2 + 2] a. v-adducts113. Little effect on the cis/trans ratio is observed. 

Asymmetric ene and Diels-Alder reactions with methyl glyoxalate. The reaction of methyl glyoxalate with isoprene catalyzed by the BINOL-titanium complex (R)-l provides not only the expected ene product (2), but also the Diels-Alder product (3), both in 97% ee (equation I). This chiral titanium complex is also an... 

What you have learned in Section 9.1.1 about electronic substituent effects explains why intermolecular hemiacetal formation from the electron-deficient carbonyl compounds methyl glyoxalate (A) and ninhydrin (B) take place quantitatively ... 

T. Hayashi and T. Shibamoto, Analysis of methyl glyoxal in foods and beverages, J. Agric. Food Chem., 1985, 33, 1090-1093. 

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