Methyl valerate

C) dl-Isoleucine.—One hundred and fifty grams (0.77 mole) of a-bromo-/3-methyl valeric acid is added to 645 cc. of technical ammonium hydroxide (sp. gr. 0.90) in a 1.5-I. round-bottomed flask. A stopper is wired in and the flask allowed to stand at room temperature for a week (Note 9). The stopper is removed and the mixture heated on a steam cone overnight to remove ammonia. The aqueous solution is concentrated under reduced pressure until bumping becomes violent (about 300 cc.). The mixture is then cooled to 150 and the crystals collected on a filter. The crystals are washed with 40 cc. of alcohol and dried. The filtrate is again concentrated to about 150 cc. and a second crop of crystals obtained. This second crop is washed with 25 cc. of water and then with 25 cc. of 95 per cent alcohol. The yield of crude product is 65 g. 

Diastereoisomers. Whereas compounds with one chiral center exist as an enantiomorphic pair, molecules with two or more chiral centers also exist as diastereoisomers (diastereomers). These are pairs of isomers with an opposite configuration at one or more of the chiral centers, but which are not complete mirror images of each other. An example is L-threonine which has the 2S, 3R configuration. The diastereoisomer with the 2S, 3S configuration is known as i-a//o-threonine. L-isoleucine, whose side chain is -CH(CH3) CH2CH3, has the 2S, 3R configuration. It can be called 2(S)-amino-3(R)-methyl-valeric acid but the simpler name L-isoleucine implies the correct configuration at both chiral centers. 

This is a general method for preparing a-bromo acids. By using exactly analogous directions -bromo- -caproic acid may be obtained in 65-70 per cent yields from w-butylmalonic ester a-bromo-isocaproic acid in 65-70 per cent yields from isobutylmalonic ester and a-bromo-/3-methyl valeric acid in 75-80 per cent yields from sec.-butylmalonic ester. 

Methyl urethane, ml81 Methyl valerate, m340... 

Methyl-l,2,4-trioxolan-3-yl)-l,2,4-trioxolane, see Isoprene diozonide, 1914 Methyltriphenylphosphonium permanganate, 3778 f Methyl valerate, 2501... 

Recently, two new beauvericins were discovered [56], These beauvericins are composed of L-phenylalanine, D-2-hydroxy-3-methyl-valerate, and D-2-hydroxyisovalerate, yielding mixed-type structures. 

Maltol Isobutyrate 2-Methoxy 3-(or 5- or 6-) Isopropyl Pyrazine 5H-5-Methyl-6,7 -dihydrocyclopenta[b]pyrazine 5-Methyl Furfural Methyl Furoate Methyl Hexanoate Methyl Isovalerate 5-Methyl 2-Phenyl 2-Hexenal Methyl Thiobutyrate Methyl Valerate P-Naphthyl Ethyl Ether Phenyl Ethyl Cinnamate Phenyl Ethyl Propionate Propyl Formate Propyl Mercaptan Salicylaldehyde 8-T etradecalactone 2-Tridecanone... 

SYNS a-AMINOISOCAPROIC ACID 2-AMINO-4-METHYLPENTANOIC ACID O-AMINO-y-METHYL-VALERIC ACID 2-AMINO-4-METHYLVALERIC ACID 1.2-AMINO-4-METHYLVALERIC ACID LEUCIN (GERMAN) LEUCINE NORVAUNE, 4-METHYL- VALERIC ACID, 2-AMINO-4-METHYL-... 

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