Chemistry Question on Nucleophilic and electrophilic substitution reactions (both aromatic and aliphatic)

Question

Find out the major product formed from the following reaction. $[ \text{Me: } -\text{CH}_3 ]$

Answer 1

Solution

Explanation 62
Step 1: Nucleophilic substitution ( $S_N2$ ) with dimethylamine ( $\text{Me}_2\text{NH}$ ): The bromine atom at one of the carbons is replaced by the nucleophile ( $\text{Me}_2\text{N}$ ) via an $S_N2$ mechanism. This forms an intermediate with a quaternary amine at the adjacent carbon.
Step 2: Deprotonation: The positively charged intermediate loses a proton ( $-\text{H}^+$ ) to stabilize the structure, forming an alkene.
Step 3: Second $S_N2$ reaction: The second equivalent of dimethylamine attacks the adjacent carbon-bromine bond, substituting the bromine atom with another $\text{Me}_2\text{N}$ group.
The final product contains two $\text{Me}_2\text{N}$ groups attached to the cyclopentane ring at adjacent positions.
The above mechanism is valid for both cis and trans isomers. Hence, the products are the same for both.