16. Conjugated Systems

Determine if the following reactions are cycloadditions, electrocyclic reactions or sigmatropic shifts.

Determine if the following reactions are cycloadditions, electrocyclic reactions or sigmatropic shifts.

Given the following reaction: ${\mathrm{1,3}}_{\mathrm{butadiene}}$ reacts with $\mathrm{ethene}$ to form $\mathrm{cyclohexene}$, what is the correct classification of this pericyclic reaction?

Identify the type of pericyclic reaction shown below: $C_{6}H{6}_6$ undergoes a reaction with heat to form $C_{6}H{6}_6$ with a new six-membered ring. What is this reaction called?

Determine if the following reactions are cycloadditions, electrocyclic reactions or sigmatropic shifts.