Methyl-2- -propanoate crystal structure

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... 

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