What is the major organic product formed when 2-(2-oxoethyl)cyclohexan-1-one is treated with NaBH ₄ followed by heating with concentrated H ₂ SO ₄ ?

Step-by-step solution

NaBH ₄ is a reducing agent that reduces both the ketone (in the ring) and the aldehyde (in the side chain) to secondary and primary alcohols, respectively. The intermediate formed is 2-(2-hydroxyethyl)cyclohexan-1-ol. Heating with concentrated H ₂ SO ₄ causes dehydration of both alcohol groups. Dehydration follows Zaitsev's rule and favors the formation of the most stable, highly conjugated system. Elimination of water from the ring and the side chain yields a conjugated diene. The double bond in the ring forms bet