Identify the major product:

CONCEPT:

Formation of Grignard Reagent and Subsequent Cyclization

• When an alkyl halide is treated with magnesium (Mg) in dry ether, a Grignard reagent (RMgBr) is formed.
• The Grignard reagent is highly reactive and can undergo intramolecular reactions, especially when a halide group is present on the same molecule.
• This can lead to the formation of cyclic structures if the conditions favor such an intramolecular attack.

EXPLANATION:

• In this reaction, the presence of two bromine atoms in close proximity leads to the formation of two Grignard reagents.
• One of the Grignard reagents can perform an intramolecular attack on the other carbon atom bearing the second bromine, leading to the elimination of MgBr₂.
• This intramolecular reaction results in the formation of a three-membered cyclopropane ring as the major product, as shown in option (2).