Exam 26: Orbitals and Organic Chemistry: Pericyclic Reactionse

Exhibit 30-2 Consider the reaction below to answer the following question(s): -Refer to Exhibit 30-2. Under what conditions, thermal or photochemical, would you carry out this reaction? Explain.

Exhibit 30-6 Consider the reaction sequence below to answer the following question(s): -Refer to Exhibit 30-6. Step 2 is an example of:

Exhibit 30-4 Consider the reaction below to answer the following question(s): -Refer to Exhibit 30-4. What type of pericyclic reaction is involved in this transformation?

There are three major classes of pericyclic reactions. Which of the following types of reactions is not an example of a pericyclic process?

For an even number of electron pairs (double bonds), which of the following rules is correct?:

Consider the reaction given below. Which of the following is correct?

The mnemonic phrase "The Electrons Circle Around", TECA, assists in predicting stereochemistry of pericyclic reactions. Describe application of this mnemonic.

Exhibit 30-5 To answer the following question(s), consider the reaction below: -Refer to Exhibit 30-5. How many pairs of electrons are involved in this pericyclic reaction?

In which type of pericyclic reaction is a σ bond broken and a new σ bond formed?

Exhibit 30-3 To answer the following question(s), consider the reaction below: -Refer to Exhibit 30-3. Explain the stereochemistry of compound Y.

Exhibit 30-4 Consider the reaction below to answer the following question(s): -Refer to Exhibit 30-4. How many pairs of electrons are involved in this pericyclic reaction?

Consider the following MO diagram for a conjugated triene. When irradiated with light of the appropriate wavelength, how many electrons will be in bonding MO's?

Exhibit 30-3 To answer the following question(s), consider the reaction below: -Refer to Exhibit 30-3. The thermal reaction which generates X is an example of:

To answer the following question(s), consider the π molecular orbitals of a conjugated diene shown below: -Refer to Exhibit 30-1. Which molecular orbital of an excited-state conjugated diene is the lowest unoccupied molecular orbital (LUMO)?

How many π MO's does the following compound have?

The photochemical cycloaddition of the structure below is related to DNA mutations causing skin cancer. Draw the structure of this dimer. Atoms other than carbon and hydrogen are labeled.

Under thermal conditions, the following substance will undergo:

Draw the structure of the product when the following substance reacts with maleic anhydride. Classify the reaction according to the number of π electrons that interact. Atoms other than carbon and hydrogen are labeled.

Exhibit 30-8 Classify each of the following sigmatropic reactions by order [x, y]. 26. ANSWER: [3, 3] POINTS: 1 27. ANSWER: [1, 7] POINTS: 1 28. ANSWER: [1, 5] POINTS: 1 Exhibit 30-9 Vitamin D₃, cholecalciferol, is synthesized under the skin by the photochemical pericyclic process shown below. Answer the following question(s) about these reactions. -Refer to Exhibit 30-9. The second step in this process is a(n):

Predict the product (including stereochemistry) when the following substance reacts under thermal conditions.