2.4- Dihydroxy-2- butanoic

Bourbonniere and Meyers (unpublished) hydrolyzed humic substances from Lake Huron sediments with 5N NaOH at 170°C for 12 hours under a nitrogen atmosphere and found the following organic acids -Ci6 and n-Cig monocarboxylic acids lactic acid, 2-hydroxybutanoic acid, 3,4-dihydroxy-butanoic acid, oxalic acid, and succinic acid. It was proposed that the smaller organic acids were derived from cellulose-related materials. 2-Hy-droxybenzoic acid, 4-hydroxybenzoic acid, 2,5-dihydroxy-3-pentenoic acid, and vanillic acid were also observed. It was believed that 4-hydroxybenzoic acid and vanillic acid originated from lignin and that the ratio of 3,4-dihy-droxybutanoic acid to vanillic acid indicates the proportion of cellulose to lignin. The proportion was in the order of fulvic acid > humic acid > humin. 

Fig. 1.—Proof of Configurations of the Racemic 2,3-Dihydroxy butanoic Acids (Illab and IVab). ...

D-fzraZ>mo-hexos-2-ulose additionally underwent elimination of glucose to give an unstable 1,2,3-tricarbonyl intermediate which led to either 3,4-dihydroxy butanoic acid or 3-deoxypentonic acids it was concluded that the formation of aldonic acid end groups via terminal aldosuloses is unimportant in the oxygen-hydrogen carbonate treatment of (1 4) linked polysac-... 

Butane, 2,3-0-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)-catalyst in homogeneous asymmetric hydrogenation, 6, 781 Butane-1,4-dioic acid, 2,2-di(indolyl)-synthesis, 4, 226 Butanenitrile, 4-hydroxy-dihydropyran synthesis from, 3, 769 Butanoic acid, -y-aryl-y-amino-synthesis, 1, 433 1-Butanol... 

CN (( )-4-[(2,4-dihydroxy-3,3-dimethyl-l-oxobutyl)amino]butanoic acid calcium salt (2 1) hopantenic acid... 

Xyloisosaccharinic acid [2,4-dihydroxy-2-(hydroxymethyl)butanoic acid] is one of the major, alkaline-degradation products of wood xylan, in particular, that of birch. The disaccharide, 2-O-D-xylopyranosyl-L-arabinose, which was isolated as a hydrolysis product of corn-cob hemicellulose, is readily degraded at 100° in 15 mM Ca(OH)2 to acidic products, primarily saccharinic acids. Xylan oligosaccharides from corn-cob hemicellulose produced 2,4-dihydroxy-2-(hydroxymethyl)buta-noic acid when exposed to 0.02 M Ca(OH)2 at 25°. However, it was noted that the xylan, itself, was stable at 100° in Af NaOH. The major acidic component of the hemicellulose fraction of slash pine Pinus el-liotti) after acid hydrolysis was identified as 4-O-methyl-D-glucuronic... 

Butanoate Methyl 4.4.4-Trifluoro EI0b,.486 (FjC —COOH + En) l-Pentene 4.5-Dihydroxy-1.1.2-tri-fiuoro- EI0b2. 147 ( -Cl2 -> En) Propanoate Ethyl 2.2.3-Trifluoro-ElOa. 667 (H5C2-COOC H5 + CoF3)... 

Erttadonine [(R,R)-6-amino-a,/3-dihydroxy-9//-pu-rine-9-butanoic acid]. 

At first we tried to address the problem with Moreau s method of kinetic resolution which has been applied with great success to compounds of central chirality (ref. 18). To our knowledge this technique has not yet been used for compounds with axial chirality. To be on safe ground, we had to calibrate the effects first with compounds of similar structure and known absolute configuration. We selected 2,2 -dihydroxy-1,1 -binaphthyl (31) as an example and reacted it in the usual way with an excess of racemic 2-phenyl butanoic anhydride in the presence of pyridine. The optical excess in the remaining anhydride was determined by means of the gas chromatographic variant of Brooks and Gilbert (ref. 19) (Scheme 6). 

Depsipeptides contain many atypical amino acids, often rmique, such as chloroisoleucine, 4-amino-3,5-dihydroxy-hexanoic acid and N-formyUeucine in cyclolithistide A, and dimethylglutamine, P-methoxytyrosine, 2,3-diamino-butanoic acid and 2-amino-2-butenoic acid in papuamides A and B (see below). Some compounds also have a halogen, such as iodine in neosiphoniamolide A. Depsipeptides are biologically similar to peptides, with cytotoxic, antitumoral, antifungal and, for some of them, antiviral properties. 

Lindemann, U., Neuburger, M., Neuburger-Zehnder, M., Wullf-Molder, D., and Wessig, R, Pho-toinduced diastereoselective pinacoHzation of 4-oxo-4-phenyl-butanoic amines to 4,5-dihydroxy-4,5-diphenyl-octanediamides,/. Chem. Soc., Perkin Trans. 2, 2029, 1999. 

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