5. Provide structures for A and B. Explain your choices using the appropriate molecular orbital diagrams (show all MO diagrams for the dien and dienophile) for reactions under thermal-vs-photochemical conditions. Show relative stereochemistry in the products. NC NO₂ hv B H₂C CH, A A

21. The following molecule may be prepared using the Diels-Alder reactions. Write the structures of the starting diene and dienophile necessary to prepare the given molecule and label them. , CO,CH,CH3 CO2₂CH₂CH3

True or False: Acetylene is a naturally occurring conjugated diene   True or False: The Diels-Alder reaction has the stereochemistry of the dienophile is retained in the product.     True or False: When looking at kinetic vs. thermodynamic products the kinetic product predominates at low temperature.   True or False: the mechanism of the Diels-Alder reaction is three π bonds break; one σ bond and two π bonds form.

Energy & Life 5. Below, six compounds labeled A - F are shown. H. NH2 NH2 .CumH H. H. H3C H2N A H. .C H;C H. H2N NH2 H3C CH3 F Rank these structures according to the nominal oxidation state of the carbon highlighted in red. Set the lowest (most negative) oxidation state as Rank 1 and and the highest (most positive) oxidation state as Rank 6, vB D E