Question

There are several reagents that can be used to effect addition to a double bond including: acid and water, oxymercuration–demercuration reagents, and hydroboration–oxidation reagents. Select all the reasons why hydroboration–oxidation reagents were chosen to effect the following transformation instead of the other reagents?
a. The reaction requires the Markovnikov product without sigmatropic rearrangement.
b. Addition with acid and water as reagents avoids sigmatropic rearrangements.
c. Hydroboration-oxidation reagents yield the anti-Markovnikov product of addition.
d. The reaction requires anti-Markovnikov product without sigmatropic rearrangement.
e. Addition with acid and water as reagents gives the Markovnikov product.
f. Hydroboration-oxidation reagents yield the Markovnikov product of addition.
g. The reaction requires sigmatropic rearrangement.

Answer 1

The answer & explanation for this question is given in the attachment below.

Answer 2

Answer:

The reaction requires anti-Markovnikov product without sigmatropic rearrangement.

Explanation:

The reaction is known to begin with the concerted syn addition of B and H across the double bond, with the boron adding to the less substituted carbon atom.

The second step of the reaction involves hydrogen peroxide and a base such as NaOH are added, NaOH deprotonates the hydrogen peroxide.

The resulting NaOOH then attacks the boron and sets up the key migration step, where the carbon-boron bond migrates to the oxygen bound to boron, breaking the weak oxygen-oxygen bond . Then the -OH expelled then returns to form a bond on the boron resulting in a deprotonated alcohol (alkoxide). The alkoxide is then protonated by water or some other comparably acidic species.

Hydroboration is a syn addition that gives an anti-Markovnikov product without sigmatropic rearrangement.