Methyl butanoate pathways

Scheme 12.51. A pathway for the formation of valine (Val, V) from isovaleric (2-methyl-butanoic) acid.

Tao HR, Lin KC. Pathways, kinetics and thermochemistry of methyl-ester peroxy radical decomposition in the low-temperamre oxidation of methyl butanoate a computational smdy of a biodiesel fuel surrogate. Combust Flame. September 2014 161 2270-2287. 

CH,Cu BF3 to give (3/ )-3-methyl[4- C]butanoate (265) in yield . Cleavage of the auxiliary afforded the e.p. acid 266 in quantitative yield. This was further converted to (25, 4/ )-[5- C]leucine (267) following the same pathway described above for e.p. (25, 45)-[5- C]leucine. A weak point of this method is that, in contrast to Oppolzer s approach for which a 2-2.5 fold excess of the organometallic reagent is sufficient, a five- to seven-fold excess is essential in order to achieve satisfactory yields. Therefore, in the radioactive case introduction of the label via the organocuprate would be very inefficient. 

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