Question

Show how you might synthesize this compound from an alkyl bromide and a nucleophile in an SN2 reaction. Use the wedge/hash bond tools to indicate stereochemistry where it exists. Only draw the reactants. Separate multiple reactants using the + sign from the drop-down menu. If there is more than one possible combination of alkyl bromide and nucleophile, draw only one combination. Do not include counter-ions, e.g., Na+, I-, in your answer.

Answer 1

Answer:

See the image 1

Explanation:

If you look carefully at the progress of the SN2 reaction, you will realize something very important about the outcome. The nucleophile, being an electron-rich species, must attack the electrophilic carbon from the back side relative to the location of the leaving group. Approach from the front side simply doesn't work: the leaving group - which is also an electron-rich group - blocks the way. (see image 2)

The result of this backside attack is that the stereochemical configuration at the central carbon inverts as the reaction proceeds. In a sense, the molecule is turned inside out. At the transition state, the electrophilic carbon and the three 'R' substituents all lie on the same plane. (see image 3)

What this means is that SN2 reactions whether enzyme catalyzed or not, are inherently stereoselective: when the substitution takes place at a stereocenter, we can confidently predict the stereochemical configuration of the product.