16. Conjugated Systems

Use the summary charts to predict the product of the following reactions. If there is more than one isomer possible, draw them

Use the summary charts to predict the product of the following reactions. If there is more than one isomer possible, draw them

Predict the product for the following reaction.

For the following electrocyclic reactions, did the substituents move in a conrotatory or disrotatory direction? Would you use heat or light to cause movement in this direction?

(a)

a. Identify the mode of ring closure for each of the following electrocyclic reactions

1.

a. Identify the mode of ring closure for each of the following electrocyclic reactions

2.

b. Are the indicated hydrogens cis or trans?

2.

b. Are the indicated hydrogens cis or trans?

1.

Which of the following are correct? Correct any false statements.

b. A conjugated diene with an antisymmetric HOMO undergoes conrotatory ring closure under thermal conditions.

Which of the following are correct? Correct any false statements.

a. A conjugated diene with an even number of double bonds undergoes conrotatory ring closure under thermal conditions.

a. Under thermal conditions, will ring closure of (2E,4Z,6Z,8E)-2,4,6,8-decatetraene be conrotatory or disrotatory?

b. Will the product have the cis or the trans configuration?

Account for the difference in the products of the following reactions:

Explain why compound A will not undergo a ring-opening reaction under thermal conditions, but compound B will.

How can this transformation be carried out using only heat or light?

Given the conditions, would you expect conrotatory or disrotatory ring closing/opening? Justify this on the basis of the molecular orbital picture.

(c)