2,3-Butanediols stereoisomers

The effect of surface structure, the role of the various crystal faces polyols on gold, sorbitol at polycrystalline and single crystal platinum electrodes, 2,3 butanediol stereoisomers at platinum single crystal electrodes, studies on the behavior of oxocarbons (squaric and croconic acids) on single crystal platinum surfaces. 

Here we see that a possible final step to the enantiomers is syn dihydroxylation of trans-2-butene. This reaotion is stereospecific and produces the desired enantiomeric 2,3-butanediols as a racemic form. Here we have made the key choice not to use c/s-2-butene. Had we chosen c/s-2-butene, our product would have been the meso 2,3-butanediol stereoisomer. 

TABLE 10.1 2,3-Butanediol Stereoisomers Produced by Different Microorganisms... 

Shen MQ, Ji XJ, Nie ZK, Xia ZF, Yang H, Huang H. (2013). Biotechnological production of 2,3-butanediol stereoisomers synthetic mechanism and realized methods. Chin J Catal, 34, 351-360. 

Ui S, HosakaT, Watanabe K, Mimura A. 1998. Discovery of anew mechanism of 2,3-butanediol stereoisomer formation in Bacillus cereus YUF-4. J Ferment Bioeng 85(l) 79-83. 

TABLE 10 Biosynthesis of Different 2 -Butanediol Stereoisomers with Engineered Heterologous Hosts... 

Only three not four stereoisomeric 2 3 butanediols are possible These three are shown m Eigure 7 10 The (2R 3R) and (2S 3S) forms are enantiomers of each other and have equal and opposite optical rotations A third combination of chirality centers (2R 3S) however gives an achiral structure that is superimposable on its (2S 3R) minor image Because it is achiral this third stereoisomer is optically inactive We call achiral mole cules that have chnahty centers meso forms The meso form m Eigure 7 10 is known as meso 2 3 butanediol... 

FIGURE 7 10 Stereo isomeric 2 3 butanediols shown in their eclipsed con formations for convenience Stereoisomers (a) and (b) are enantiomers of each other Structure (c) is a diastereo mer of (a) and (b) and is achiral It is called meso 2 3 butanediol... 

Fischer projection formulas can help us identify meso forms Of the three stereoisomeric 2 3 butanediols notice that only in the meso stereoisomer does a dashed line through the center of the Fischer projection divide the molecule into two mirror image halves... 

Problem 9.36 The ds and trans isomers of 2,3-dimethyloxirane both react with OH to give 2,3-butanediol. One stereoisomer gives a single achiral product, and one gives two chiral enantiomers. Which epoxide gives one product and which gives two ... 

The most popular lands of the diols for asymmetric synthesis are bis-secondary diols that have a C2 axis of symmetry [212]. The presence of the symmetry axis avoids the formation of diastereoisomeric esters or acetals [213], (1R, 27 )-Cyclohexanediol 1.34 (n = 1) has been used as an auxiliary in asymmetric cyclopropanation [214] and (IS, 2S)-cycloheptanediol 1.34 (n = 2) in 1,4-addition of cuprates[157], Dioxolane derivatives of 1.34 have been used for asymmetric P-ketoester alkylations [215] and cuprate 1,4-additions [216]. Linear 1,2-diols 1.35 (R = Me, i-Pr, c-CgH j, Ph) and functionalized 1,2-diols 1.36 (Y = COOalkyl, CONR 2, CH2OR ) are readily available from optically active tartaric acids 1.36 (Y = COOH). Acetals derived from these diols are valuable reagents m asymmetric synthesis [173, 213, 217], as the related 1,3-diols 1.37. Acetals of 1,3-butanediol 137 (R = Me, R = H) have also been used. When these acetals are formed from aldehydes under thermodynamic conditions, one 1,3-di-oxane stereoisomer often predominates. In this favored isomer, the substituent from the aldehyde and the methyl group from 1.37 are both in equatorial orientar... 

Problem 17.47. Draw the stereoisomers, if any, of each of the following (a) 1,1-dimethyl-l-propanol, (b) 2-methyl-l-propanol, (c) 1-propanol, id) 1-methyl-1-propanol, (e) 3-chloro-2-butanol, (/) 2,3-butanediol. 

Butanediol has two stereocenters (C-2 and C-3). There are only three stereoisomers, one pair of enantiomers and one meso compound, since the two stereocenters have the same four different substituents ... 

Cis- and trans 3,4-thiolandiols (463 and 464) were obtained by reaction of sodium sulfide with l,4-dichloro-2,3-butanediol. Oxidation of both cyclic hydroxysulfldes gave the corresponding sulfoxides, 465 (a mixture of two stereoisomers) and 466. After esterification the sulfoxides were subjected to Pummerer rearrangement. From 465 (both stereoisomers) all-a s triester sulfide (467) was obtained. However, cyclic phenylboronate ester gave under the same conditions a trans 1-0-acetate (468). The trans diester sulfoxide 466 yielded both of the possible rearranged products, 470 and 471, in roughly equal proportions. 

Butanediol The Fischer projection fonnulas of the three stereoisomers are... 

Consider another example, a synthesis that requires stereochemical control the synthesis of the enantiomeric 2,3-butanediols, (2/ ,3/ )-2,3-butanediol and (25,35)-2,3-butanediol, from compounds of two carbon atoms or fewer, and in a way that does not produce the meso stereoisomer. 

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