When 2-methylhept-5-en-2-ol is treated with catalytic H ^+ and heat, followed by the addition of HBr , a major cyclic product is formed. The IUPAC name of this major product is:

Step-by-step solution

Acid-catalyzed dehydration of 2-methylhept-5-en-2-ol generates a stable tertiary carbocation at C2. Intramolecular cyclization occurs as the C5=C6 pi bond attacks the C2 carbocation. Attack by C6 forms a kinetically and thermodynamically favored 5-membered ring, leaving a secondary carbocation at C5. Attack by C5 is disfavored as it would form a more strained 4-membered ring. The secondary carbocation at C5 is adjacent to C6, which bears a methyl group and a hydrogen atom. A 1,2-hydride shift occurs from C6 to C5,