Question

Which of the following compound would yield trialkyl borane as shown below when treated with $B{H}_3$ and THF ?

• A. 2 - Methyl but-1-ene
• B. 2 - Methyl but-2-ene
• C. 3 - Methyl but-1-ene
• D. 3 - Methyl but-1-ene

Answer 1

The correct option is D

3 - Methyl but-1-ene

The given trialkyl borane is:

For the reaction, in general $B{H}_3$ is prepared in situ (as $B{H}_3$ exists as a dimer $B_2{H}_6$).

Hydroboration happens according to Anti-Markovnikovi addition.

This means that in the reaction intermediate Boron atom is attached to the carbon atom of the alkene with the higher number of Hydrogen atoms.

For example,

For our solution, the alkene should be

Ans: (d)