55.
What is the correct classification of the following pericyclic reaction?
+
A)
electrophilic addition
B)
sigmatropic rearrangement
C)
cycloaddition
D)
electrocyclic reaction
E)
C & D
Ans:
C
56.
Which statement is NOT true about the Diels-Alder reaction?
A)
It is a [4+2] cycloaddition reaction.
B)
The diene must be in the s-cis conformation to react.
C)
Most Diels-Alder reactions are reversible.
D)
It is a sigmatropic rearrangement.
E)
Electron donating groups on the diene and electron withdrawing groups on the
dieneophile favor product formation.
Ans:
D
57.
The Diels Alder reaction is a concerted reaction, which means
A)
The product contains a cyclic ring
B)
The diene must be in the s-cis conformation to react.
C)
All changes in bonding (bond making and bond breaking) occur simultaneously.
D)
It is an endothermic reaction
E)
Both exo and endo products are formed
Ans:
C
58.
Which of the following dienes can undergo the Diels-Alder reaction?
I
II III IV
A)
I
B)
II
C)
III
D)
IV
E)
All of the these
59.
Which of the following diene(s) can not undergo the Diels-Alder reaction?
III III IV
A)
I
B)
II
C)
III
D)
IV
E)
I & IV
Ans:
E
Ans:
II
60.
Which one of the following dienophiles is least reactive in the Diels-Alder reaction?
O
H
O
OCH3
O
H3CO
CN OCH3NO2
III III IV V
A)
I
B)
II
C)
III
D)
IV
E)
V
61.
Which one of the following dienophiles is most reactive in the Diels-Alder reaction?
OCH3
I
III
IV
O
O
O
II
V
A)
I
B)
II
C)
III
D)
IV
E)
V
Ans:
C
Ans:
D
62.
Predict the product for the following Diels-Alder reaction.
O
+
OOCCH3
O
CCH3
O
III III IV
A)
I
B)
II
C)
III
D)
IV
E)
none of these
Ans:
B
63.
Predict the product for the following Diels-Alder reaction.
COCH3
O
+
OCH3
O
OCH3
OCOCH3
O
CCH3
O
III III IV
A)
I
B)
II
C)
III
D)
IV
E)
None of these
64.
Predict the product for the following Diels-Alder reaction.
C
C
C
+
C
N
N
Ans:
B
65.
Predict the major product for the following Diels-Alder reaction.
C
OH
OH
C
O
O
+
66.
Predict the major product for the following Diels-Alder reaction.
+
67.
Predict the major product for the following Diels-Alder reaction.
Cl OCCH3
O
+
O
68.
Predict the product for the following Diels-Alder reaction.
+
O
O
Excess
69.
Predict the major product for the following Diels-Alder reaction.
O
O
O
+
70.
Compound A is one of the intermediate products in the synthesis of the corticoid
hormone cortisone. Provide the structure of compound A.
H3CH2CO
O
O
+Compound A
71.
Predict the major product for the following Diels-Alder reaction.
H3CO
O2N
HCH2OCH3
H
+
Ans:
72.
Predict the major product for the following intramolecular Diels-Alder reaction and
provide a curved arrow mechanism for the formation of the product.
H3CO OCH3
O
73.
The following Diels-Alder reaction product is an intermediate in the synthesis of
Estrone. Provide the structure of the product.
H3CO
O
O
+
74.
The following Diels-Alder reaction product is an intermediate in the synthesis of
Cholesterol. Provide the structure of the product.
O
O
H
3
CO
CH
3
+
75.
What diene and dienophile would react to give the following Diels-Alder product?
COH
O
COH
O
COH
COH
O
O
COH
COH
O
O
COH
COH
O
O
III
III
COH
COH
O
O
IV
+
+
++
A)
I
B)
II
C)
III
D)
IV
Ans:
B
76.
What diene and dienophile would react to give the following Diels-Alder product?
III III
IV V
+
+
++
+
A)
I
B)
II
C)
III
D)
IV
E)
V
Ans:
B
77.
What diene and dienophile would react to give the following Diels-Alder product?
CCH3
O
I
III
IV V
+
+
+
+
II
+
CCH3
O
CCH3
O
CCH3
O
CCH3
O
CCH3
O
A)
I
B)
II
C)
III
D)
IV
E)
V
Ans:
B
78.
What diene and dienophile would react to give the following Diels-Alder product?
CN
CN
III
CN
CN
III
CH2CH3
V
IV
CN
CN
++
+
+
+
CN
NC
CN
CN
A)
I
B)
II
C)
III
D)
IV
E)
V
79.
What diene and dienophile would react to give the following Diels-Alder product?
Ans:
D