Question 1

Is the thermal [4+2] cycloaddition between allyl anion and ethylene an allowed one? To answer, draw the HOMO of allyl anion and the LUMO of ethylene, and comment on the symmetry match of the two.

Accepted Answer

The answer of Is the thermal [4+2] cycloaddition between allyl...

Question 2

The following [3+2] cycloaddition was reported in Organic Letters, 2011, 402. Predict whether the reaction would be thermally or photochemically promoted. Justify your answer by showing overlap of the correct molecular orbitals. Assume the alkene is the electrophile.

Accepted Answer

The answer of The following [3+2] cycloaddition was reported in...

Question 3

Provide the structure of the major organic product in the following reaction.

Accepted Answer

The answer of Provide the structure of the major organic...

Question 4

Assuming kinetic conditions, provide the correct stereochemistry and regiochemistry of the major product of the following reaction.

Accepted Answer

The answer of Assuming kinetic conditions, provide the correct stereochemistry...

Question 5

Provide the major organic product of the following reaction.

Accepted Answer

The answer of Provide the major organic product of the...

Question 6

Consider the possible thermal [4+4] cycloaddition of two molecules of 1,3-butadiene to generate cycloocta-1,5-diene. Show the HOMO/LUMO interaction which would result, and use this interaction to predict whether the proposed cycloaddition could occur.

Accepted Answer

The answer of Consider the possible thermal [4+4] cycloaddition of...

Question 7

Assuming kinetic conditions, draw the major product of the reaction below. Include correct stereochemistry.

Accepted Answer

The answer of Assuming kinetic conditions, draw the major product...

Question 8

Dicylopentadiene results when cyclopentadiene reacts with itself in a Diels-Alder reaction. Provide the structure of dicyclopentadiene. Pay particular attention to stereochemical detail.

Accepted Answer

The answer of Dicylopentadiene results when cyclopentadiene reacts with itself...

Question 9

Provide a picture of the HOMO of 1,3,5-hexatriene.

Accepted Answer

The answer of Provide a picture of the HOMO of...

Question 10

Why does the (E,E)-isomer of 2,4-hexadiene react much more rapidly with dienophiles than does the (Z,Z)-isomer?

Accepted Answer

The answer of Why does the (E,E)-isomer of 2,4-hexadiene react...

Question 11

What are the structures of A, B, and C?

Accepted Answer

The answer of What are the structures of A, B,...

Question 12

The following Diels-Alder reaction was featured in Tet. Lett. 2011, 960. Predict the structure of the starting materials.

Accepted Answer

The answer of The following Diels-Alder reaction was featured in...

Question 13

Indicate whether the following cyclization, conducted under thermal conditions, is symmetry allowed. Justify your answer by showing whether the overlapping orbitals in the transition state generate a symmetry-allowed or symmetry-forbidden scenario. Treat ethylene as the nucleophile.

Accepted Answer

The answer of Indicate whether the following cyclization, conducted under...

Question 14

Predict the outcome of the reaction shown below.

Accepted Answer

The answer of Predict the outcome of the reaction shown...

Question 15

Provide the major organic product of the following reaction.

Accepted Answer

The answer of Provide the major organic product of the...

Question 16

What characterizes a pericyclic reaction?

Accepted Answer

The answer of What characterizes a pericyclic reaction?...

Question 17

Provide a picture of the LUMO of 1,3,5-hexatriene.

Accepted Answer

The answer of Provide a picture of the LUMO of...

Question 18

Provide the structure of the major organic product in the following reaction.

Accepted Answer

The answer of Provide the structure of the major organic...

Question 19

Why does the diene shown below fail to undergo a Diels-Alder reaction with even the most reactive dienophiles?

Accepted Answer

The answer of Why does the diene shown below fail...

Question 20

Predict the major product of the following reaction:

Accepted Answer

The answer of Predict the major product of the following...

Quiz 15: Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy

Is the thermal [4+2] cycloaddition between allyl anion and ethylene an allowed one? To answer, draw the HOMO of allyl anion and the LUMO of ethylene, and comment on the symmetry match of the two.

The following [3+2] cycloaddition was reported in Organic Letters, 2011, 402. Predict whether the reaction would be thermally or photochemically promoted. Justify your answer by showing overlap of the correct molecular orbitals. Assume the alkene is the electrophile.

Provide the structure of the major organic product in the following reaction.

Assuming kinetic conditions, provide the correct stereochemistry and regiochemistry of the major product of the following reaction.

Provide the major organic product of the following reaction.

Consider the possible thermal [4+4] cycloaddition of two molecules of 1,3-butadiene to generate cycloocta-1,5-diene. Show the HOMO/LUMO interaction which would result, and use this interaction to predict whether the proposed cycloaddition could occur.

Assuming kinetic conditions, draw the major product of the reaction below. Include correct stereochemistry.

Dicylopentadiene results when cyclopentadiene reacts with itself in a Diels-Alder reaction. Provide the structure of dicyclopentadiene. Pay particular attention to stereochemical detail.

Provide a picture of the HOMO of 1,3,5-hexatriene.

Why does the (E,E)-isomer of 2,4-hexadiene react much more rapidly with dienophiles than does the (Z,Z)-isomer?

What are the structures of A, B, and C?

The following Diels-Alder reaction was featured in Tet. Lett. 2011, 960. Predict the structure of the starting materials.

Indicate whether the following cyclization, conducted under thermal conditions, is symmetry allowed. Justify your answer by showing whether the overlapping orbitals in the transition state generate a symmetry-allowed or symmetry-forbidden scenario. Treat ethylene as the nucleophile.

Predict the outcome of the reaction shown below.

Provide the major organic product of the following reaction.

What characterizes a pericyclic reaction?

Provide a picture of the LUMO of 1,3,5-hexatriene.

Provide the structure of the major organic product in the following reaction.

Why does the diene shown below fail to undergo a Diels-Alder reaction with even the most reactive dienophiles?

Predict the major product of the following reaction: