ADVANCED ORGANIC CHEMISTRY EXAMINATION:
COMPREHENSIVE PERICYCLIC REACTIONS STUDY
GUIDE
SECTION A: MULTIPLE CHOICE QUESTIONS (20 Marks)
Instructions: Select the single best answer for each question.
The Diels-Alder reaction is classified as which type of pericyclic reaction?
(A) A cycloaddition
(B) An electrocyclic reaction
(C) A sigmatropic rearrangement
(D) A group transfer reaction
Answer: (A)
According to the Woodward-Hoffmann rules, the thermal cyclization of 1,3,5-hexatriene
proceeds via which mode?
(A) Disrotatory
(B) Conrotatory
(C) Suprafacial
(D) Antarafacial
, Answer: (B)
Which of the following statements is true for a photochemical [2+2] cycloaddition?
(A) It proceeds suprafacially on both components.
(B) It proceeds antarafacially on both components.
(C) It is forbidden by the Woodward-Hoffmann rules.
(D) It forms a four-membered ring with retention of stereochemistry.
Answer: (A)
A [1,5] sigmatropic shift of hydrogen in a 1,3-pentadiene system is allowed thermally if it
proceeds through a:
(A) Suprafacial shift with a 4n electron system
(B) Antarafacial shift with a 4n electron system
(C) Suprafacial shift with a 4n+2 electron system
(D) Antarafacial shift with a 4n+2 electron system
Answer: (C)
The Cope rearrangement is a:
(A) [1,3] sigmatropic rearrangement
(B) [1,5] sigmatropic rearrangement
(C) [3,3] sigmatropic rearrangement
(D) [2,2] cycloaddition
Answer: (C)
COMPREHENSIVE PERICYCLIC REACTIONS STUDY
GUIDE
SECTION A: MULTIPLE CHOICE QUESTIONS (20 Marks)
Instructions: Select the single best answer for each question.
The Diels-Alder reaction is classified as which type of pericyclic reaction?
(A) A cycloaddition
(B) An electrocyclic reaction
(C) A sigmatropic rearrangement
(D) A group transfer reaction
Answer: (A)
According to the Woodward-Hoffmann rules, the thermal cyclization of 1,3,5-hexatriene
proceeds via which mode?
(A) Disrotatory
(B) Conrotatory
(C) Suprafacial
(D) Antarafacial
, Answer: (B)
Which of the following statements is true for a photochemical [2+2] cycloaddition?
(A) It proceeds suprafacially on both components.
(B) It proceeds antarafacially on both components.
(C) It is forbidden by the Woodward-Hoffmann rules.
(D) It forms a four-membered ring with retention of stereochemistry.
Answer: (A)
A [1,5] sigmatropic shift of hydrogen in a 1,3-pentadiene system is allowed thermally if it
proceeds through a:
(A) Suprafacial shift with a 4n electron system
(B) Antarafacial shift with a 4n electron system
(C) Suprafacial shift with a 4n+2 electron system
(D) Antarafacial shift with a 4n+2 electron system
Answer: (C)
The Cope rearrangement is a:
(A) [1,3] sigmatropic rearrangement
(B) [1,5] sigmatropic rearrangement
(C) [3,3] sigmatropic rearrangement
(D) [2,2] cycloaddition
Answer: (C)
