Which of the following is the correct IUPAC name for a compound with a $\mathrm{cyclohexenone}$ ring, $\mathrm{phenyl}$ groups at positions $3$ and $5$, and an $\mathrm{ethoxycarbonyl}$ group at position $6$?

• A. $6-\mathrm{ethoxycarbonyl}-3,5-\mathrm{diphenyl}-\mathrm{cyclohex}-2-\mathrm{en}-1-\mathrm{one}$
• B. $3,5-\mathrm{diphenyl}-6-\mathrm{ethoxycarbonyl}-\mathrm{cyclohexanone}$
• C. $6-\mathrm{ethoxycarbonyl}-3,5-\mathrm{diphenyl}-2-\mathrm{cyclohexenone}$
• D. $2-\mathrm{cyclohexenone}-3,5-\mathrm{diphenyl}-6-\mathrm{ethoxycarbonyl}$

Answer: (A)

Verified step by step guidance

1. Identify the parent structure: The compound is based on a cyclohexenone ring, which is a cyclohexane ring with a double bond and a ketone. The correct parent name is derived from 'cyclohex-2-en-1-one', indicating the double bond starts at carbon 2 and the ketone is at carbon 1.
2. Number the ring to give the substituents the lowest possible numbers while respecting the priority of functional groups. The ketone carbon is assigned position 1, and the double bond starts at carbon 2. Numbering proceeds around the ring to assign substituents at positions 3, 5, and 6.
3. Identify and name the substituents: There are phenyl groups at positions 3 and 5, which together are named as '3,5-diphenyl'. There is an ethoxycarbonyl group at position 6, which is a carboxylic acid derivative substituent.
4. Arrange the substituents in alphabetical order when writing the name, ignoring prefixes like di-, tri-. 'Ethoxycarbonyl' comes before 'diphenyl' alphabetically, so the ethoxycarbonyl substituent at position 6 is named first, followed by the diphenyl groups at positions 3 and 5.
5. Combine all parts to form the full IUPAC name: start with the substituents and their positions, then the parent name with locants for the double bond and ketone. The final name structure is '6-ethoxycarbonyl-3,5-diphenyl-cyclohex-2-en-1-one'.