Which of these is not suitable for the synthesis of 3-methyl

Last updated: 8/7/2022

Which of these is not suitable for the synthesis of 3-methyl butanoic acid? treat 1-bromo-2-methyl-propane with Mg, ether, than treat with CO2, then aqueous acid workup 3-methyl but-1-ene treated with B₂H6-THF, followed by H₂O₂ in NaOH; then treat with Na₂Cr₂O7 in aq. H₂SO4 4-methyl pent-1-ene treated with hot acidic KMnO4 2-bromo-3-methyl butane treated with NaCN followed by hydrolysis (H3O+, heat)