2.3- Dimethylheptanoic acid

Alkaline permanganate oxidation is frequently employed. Examples are 2,6-dimethylheptanoic acid (45%) from 3,7-dimethyI-l-octene, w-ethyl-phenylacetic acid (24%) ° from m-ethylallylbenzene, and azelaic acid (36%) ° from ricinoleic acid. 

Internal standard 7-(2,5-dimethylphenoxy)-2,2-dimethylheptanoic acid Limit of detection 100 ng/mL... 

Would you expect that any substantial amount of 6,6-dimethylheptanoic acid would be found in (3) (above) Explain. 

An enantioselective route to 1,3-dithiane 1-oxide (33) (R = R = H) was subsequently developed [69]. It involves asymmetric oxidation of (32) (R = pivaloyl, R = H) by cumene hydroperoxide in presence of the chiral titanium complex. The syn/anti mixture (around 90% ee for each diastereoisomer) is recrystallized and then deacylated, giving the desired product in 80% yield. A recent application of this chemistry is the asymmetric synthesis of enantiopure (R)-(-)-2,6-dimethylheptanoic acid in two steps from (33) (R = C(0)Et, R = Et) [70]. The reaction involves a fully stereoselective methylation in the a-position of the keto group, followed by basic deacylation, which also regenerates enantiopure 2-ethyl-l,3-dithiane 1-oxide (33) (Ri = H, R = Et). A range of a-arylpropanoic acids have since been prepared by similar routes in high ee s. [162]... 

Studies within the Page group geared toward the synthesis of (f )-(-)-2,6-dimethylheptanoic acid [129], a simple natural produet derived from citronellal, have proved effective. This species contains a carboxylic acid function substituted at the a-carbon atom, a feature common to many analgesic compounds. This synthesis promises the first application of DiTOX as a chiral building block in organic synthesis... 

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