D-a-Methylbutyric acid

On hydrolysis with methanolic potash protoveratridine yields the alkamine germine, C27H430gN, and d-(—)-a-methylbutyric acid, [ ]d — 23.1° (water) (51). 

PROPERTIES AND DERIVATIVES. Germidine, Cj4H6 OioN, is dimorphic and melts at 198-200° or 230-231° (dec.) (dil. ethanol) [a]o + 13 (chloroform), —11° (pyridine) thiocyanate, m.p. 242-244 (dec.) (dil. methanol). Alkaline hydrolysis of germidine gave rise to germine and a mixture of acetic and d-(—)-a-methylbutyric acid, which were obtained in the form of their p-phenylphenacyl esters (19). 

Base Z, CjaHj OaN. This name was provisionally applied to a syrupy base which yielded a crystalline oxalate, Bg. HgCg04, m.p. 296-7°, a hydrobromide m.p. 219-20° [a]f ° + 2-9° (c = 6 HgO), a methiodide m.p. 801°, and a picrate m.p. 172°. On hydrolysis it furnished nortropine (tropigenine, p. 75) and a liquid acid, eventually shown to be a mixture of isovaleric and d-a-methylbutyric acids. Base Z is therefore a mixture of isovalerylwortropeine (which has been named poroidine) and d-a-methyl-butyrylnortropeine (isoporoidine). Separation has not been effected but the two components have been synthesised and described. 

The tropane alkaloids, which have been isolated from various species of the plant families, Convolvulaceae, Dioscoraceae, Erythroxylaceae, and Solonaceae, all exhibit common structural features. They are all esters of organic acids (atropic, benzoic, cinnamic, isovaleric, d-a-methylbutyric, tiglic, tropic, truxillic and veratric) combined with one of a series of bicyclic hydramines (methylecgonine, nortropine, pseudotropine, scopine, tropine and others) which may be conveniently represented in general form by I . 

Alkaline hydrolysis of germerine yields the alkamine germine, D-(—)-o-methylbutyric acid, [ ]d — 22°, —25 (water), and (-l-)-o-hydroxy-a-methylbutyric acid, m.p. 72-73°, [a]o + 4.4° (water). With baryta at 40° it yields protoveratridine on partial hydrolysis and ultimately germine (19, 51). 

Juloerotine, C18H24O3N2 (mp 109° [a]D —9° in CHCI3, -50° in MeOH) was first reported by Anastasi (135) but its nonbasic nature and its structure were only determined recently 136). Extensive spectral studies indicated the nature of the functional groups and complete acid hydrolysis resulted in (8-phenethylamine, (+ )-a-methylbutyric acid, and L-( + )-glutamic acid. These fragments show that juloerotine is LIV. Julocroton subpannosus Muell. Arg. and J. camporum ( ) also contain juloerotine. 

R. Carney, of Zoecon Corporation, Palo Alto, Calif., who is collaborating in this research, developed a synthesis of 96% ee (R)-2-methylbutyric acid from D-isoleucine (Figure 14). Another approach that involved HPLC purification of diastereomeric amides with subsequent cleavage of the amide link gave the R-acid in 94% ee. 

The structure of the western corn rootworm sex pheromone is 8-methyl-2-decanol propanoate (] 6) and four stereoisomers are possible (Figure 7). In our synthesis (3), we coupled a chiral 5-carbon unit to a 6-carbon fragment that had the requisite substitution to allow resolution at the oxygenated carbon. As mentioned earlier, (S)-2-methylbutyric acid was available to us from the alcohol. D-Isoleucine served as a source for the (R)-acid. Nitrosation, followed by decarboxylative oxidation of the intermediate hydroxyacid led to the (R)-2-methylbutyric acid in 96% ee. The process of fractional crystallization was... 

Methyl-l-nitrobutane, A"33.8 Valine, A4.19, A"15 Norvaline, A10.15, A"8 2-Amino-2-methylbutyric acid, A40.9 4-Amino-2-methylbutyric acid, A34.5 4-Amino-3-methylbutyric acid, A27.16 4-Aminopentanoic acid, A 14.14, A"6, A"8 [4- C]Valine, D 3.10... 

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