2-Hydroxy-3-methylvaleric acid

Synthesis of the optically pure (25, 35, 4i )-4-amino-3-hydroxy-2-methylvaleric acid (18) has been achieved from L-rhamnose by conversion to 5-deoxy-L-arabino-7 -lactone (10) ° (Scheme 2)f Treatment of 10 with excess benzylamine in methanol afforded the... 

Updated Entry replacing H-60192 3-Hydroxy-2-methylvaleric acid, SCI [28892-73-1]... 

Janolusimide is a tripeptide isolated from Janolus cris-tatus harvested in the Bay of Naples. This derivative is particularly unusual because it is made up of three rare or original amino adds N-methyl-L-alanine, 4-amino-3-hydroxy-2-methylvaleric acid, and a pyrroHdine-dione tri-substituted with an isopropyl group and two geminated methyl groups (Sodano and Spinella, 1986). Janolusimide is neurotoxic to the mouse, with an LD50 of 5 mgkg . Its possible biosynthesis from alanine, propionate and isobutyrate has been proposed. 

In branched-chain fatty acids the hydrogen on a tertiary carbon atom can be replaced by hydroxyl by means of alkaline permanganate solution e.g., 2-hydroxy-2-methylpropionic acid, HO—C(CH3)2—C02H, is obtained from isobutyric acid, and 4-methyl-y-valerolactone is obtained from 4-methylvaleric acid.227... 

Fig. 3.22. GC separation of keto and hydroxy acids from the urine of a patient with maple syrup urine disease. Top chromatogram, the patient before dietary treatment middle chromatogram, the same patient after two days on a diet bottom chromatogram, a mixture of reference compounds. Peaks 1, lactic acid 2, 2-hydroxyisobutyric acid 3, 2-hydroxybutyric acid 4, pyruvic acid 5, 3-hydroxyisobutyric acid 6, 3-hydroxybutyric acid 7, 2-hydroxyisovaleric acid 8, 2-ketobutyric acid 9, malonic acid (internal standard) 10, 2-methyl-3-hydroxybutyric acid 11, 2-hydroxy-n-valeric acid 12. methylmalonic acid 13, 3-hydroxyisovaleric acid 14a and b, 2-ketoisovaleric acid IS, acetoacetic add 16, 2-hydroxyisocaproic acid 17, 2-hydroxy-3-methylvaleric acid 18a, L-2-keto-3-methylvaleric add 18b, D-2-keto-3-methyl-valeric acid 19, 2-ketoisocaproic acid. Reproduced from [386],...

Tetranortriterpenoids.—The full structures of heudelottins C (64), E (65), and F (66), from Trichilia heudelottii, have been solved." The esterifying acids include 2-hydroxy-3-methylbutanoic acid, 2-hydroxy-3-methylvaleric acid, and... 

Hydroxy-3-methylvaleric acid. P-Methyl-P-ethylhy dr aery lie acid... 

Following the ketol condensation to yield a-acetolactate and a-aceto-a-hydroxybutyrate the question arises as to whether the pinacol rearrangement occurs first to form a-keto-jS-hydroxyisovaleric acid and a-keto-i9-hydroxy- 8-methylvaleric acid (Fig. 7, III), or whether there is prior reduction. The evidence favoring pinacol rearrangement followed by reduction of the a-keto- 3-hydroxy acids is that enzymes have been found in Neurospora and E. coli which catalyze the reduction of synthetically prepared a-keto-(8-hydroxyisovaleric acid and a-keto-j8-hydroxy-/3-methyl-valeric acid to the corresponding a,/8-dihydroxy acids (166, 167). 

X 10 M for a-keto-j3-hydroxy- 8-methylvaleric acid and of 1.6 X 10 M for a-keto-j8-hydroxyisovaleric acid. 

The butyric acid derivative (19) has been synthesized by thermal rearrangement of the isoxazolidine (18) obtained by 1,3-dipolar addition of a nitronic ester to methyl acrylate. Nitrous acid deamination of (25,35)-isoleucine has been found to give predominantly (95 %) (25, 35)-2-hydroxy-3-methylvaleric acid (20). 

Figure 3 The total ion ourrent ohromatogram obtained for the organic acids isolated from the sodium borodeuteride-treated urine of a patient with maple syrup urine disease. The ratios of the H-labelled to unlabelled analogues for 2-hydroxyisovaleric acid, 2-hydroxyisooaproio acid and the two 2-hydroxy-3-methylvaleric acid diastereomers are respectively 0.24, 34.5, 30.0 and 3.70.

Truscott, R. J.W., Pullin, C.J., Halpern, B., Hammond, J., Haan, E. andDanks, D.M. (1979), The identification of 3-keto-2-methylvaleric acid and 3-hydroxy-2-methyl-valeric acid in a patient with propionic acidemia. Biomed. Mass Spectrom., 6,294. 

Numerous organic acids have been identified in tobacco. These volatile, nonvolatile, and amino acids have been discussed in-depth by Tso [see Chapter 24 in (3973)]. The major nonvolatile acids are 2-hydroxy-l,2,3-propanetricarboxylic (citric), hydroxybutanedioic (malic), and ethanedioic (oxalic). The minor nonvolatile acids are hydroxyacetic (glycolic), butanedioic (succinic), propanedioic acid (malonic), butene-dioic (E) (fumaric acid), and 2-oxopropanoic (pyruvic). The major volatile acids in tobacco are acetic and formic acid minor volatile acids are propanoic, 2-furancarboxylic acid (2-furoic), benzoic, a-methylbutyric, P-methylvaleric, and numerous others. Over forty amino acids and related compounds have been identified in tobacco [Leffingwell (2337)]. 

Bicarbonate hydrolysis removed first the 11- and then the 12-substituent it was shown by mass spectroscopy that heudelottin E (18) had a formate at C-11, a 2-hydroxy-3-methylvalerate at C-12 and a 2-hydroxy-3-methylbutyrate at C-7. Heudelottin F (19) was acetylated in the side chain at C-12, while heudelottin C (20) was the 11-deformyl derivative of F. These compounds are of interest as they are the simplest ones containing the 11P-formyloxy-12oc-(2-hydroxy-3-methylvaleryloxy) system which has been found very commonly in the complex compounds of the prieurianin group. Acid treatment of heudelottin, like that of the simpler havanensin, very readily isomerises the oxide to a 15-ketone (22), but by alkaline hydrolysis of heudelottin it is possible to obtain the epoxy alcohol (17)... 

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