Question

Provide the missing compounds for each step in the following synthesis. Please use Br as your leaving group, should you require one. Be sure to show stereochemistry explicitly where necessary, using wedges and dashes.

Please draw all four bonds at the sp2 carbons and at chiral carbons, including those to hydrogen. Provide the structure for compound B in the given synthesis. Be sure to consider the stereochemistry of the product as well as the mechanism for the reaction of Br2 with compound B when formulating your answer. CH3 NaOCH3 Br2H Br H3C CH3 CH3OH a "2-bromo- 3-methylpentane" enantiomer Synthetic target

Answer 1

Answer 2

H CH3 NaOCH3 ) Br2 CH Y CH3 CH3OHHC Y CH3 Br H3C CH3 CH3 (2R,3R)-2-bromo- 2 -3-methylpent-2-ene (2S,3S)-2,3-dibromo 3-methylpentane -3-methylpentane + Br H (2R,3R)-2,3-dibromH3C 0-3-methylpentane Br" H3C CH3

The first step 2-Bromo-3-methyl pentane undergoes elimination reaction via E2 mechanism. Which gives the product B: 2E-3-methylpent-2-ene. Upon bromination of "B" it gives a mixture of enantiomers as it goes via cyclic bromonium ion intermediate.