The Stereochemistry of 3-Hydroxy-2-methylbutyric Acid

Abstract

Four stereoisomers of methyl 3-hydroxy-2-methylbutyrate (I), (+)-threo-I, (−)-threo-I, (+)-erythro-I, and (−)-rythro-I, were prepared, and their absolute configurations were determined. The configurations of (+)-threo-I, [α]D20+36.80° (c 5, methanol) and (+)-erythro-I, [α]D20+14.32° (c, 5, methanol) were assigned to (2S, 3S) and (2S, 3R) respectively.

Preparation of Streochemically Pure Sex Pheromone Components of the Pine Sawfly (Neodiprion sertifer) and Field Tests of the Synthetic Compounds

“…The IR and IH-NMR data of this compound were consistent with reported data. 16 ) Analytical GLC (90°C) of the sample showed a single peak at tR 2.9min corresponding to (2S,3S)-9. No detectable signals were observed at tR 2.3 or and 3.1 min, these corresponding to (S)-5 and (2R,3S)-9, respectively.…”

“…The IR and IH-NMR data of this compound were consistent with reported data. 16 ) Analytical GLC (90°C) ofthe sample showed a single peak at t R 3.1 min, which corresponded to that of (2R,3S)-9. In the IH-NMR spectrum, no detectable signals of the antipode were observed when the spectrum was measured with 10mg of the sample and 7mg of (+ )Eu[hfmch in 0.5 ml of COCI3 • (2S,3S)-and (2R,3S)-2-Methyl-3-tetrahydropyranyloxy-l-butanol (2).…”

Achaetolide-II isolated from Helminthosporium velutinum TS28

“…Methanolysis of 4 under basic conditions afforded methyl threo-3-hydroxy-2-methylbutanoate (6a) 25,26 and the previously prepared diol 7a. 10 These were further converted into (S)-and (R)-MTPA esters (S)-6b, (R)-6b, (S)-7b and (R)-7b.…”

“…The 1 H NMR spectral data of this sample were accorded well with threo-methyl 3-hydroxy-2-methylbutanoate but not with the corresponding erythro-isomer. 25 …”

Carbohydrate chiral-pool approach to four enantiomerically pure 2-naphthylmethyl 3-hydroxy-2-methylbutanoates

“…Preliminary results of this work were published. 7 The syntheses of chiral 2 with variable enantiomeric purities were realized before via aldol condensations [8][9][10][11][12][13][14][15][16] (in some cases enzymatic resolution step was involved 8,9 ), enantioselective reductions of carbonyl group, 17,18 or by acetoxymercuration followed by chiral resolution. 19 In this work, we opted for the application of monosaccharides to obtain the enantiomerically pure targets 20, 33, 48, and 56 in order to avoid a necessity to perform chiral separations, which can be difficult.…”