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

Provide the necessary synthetic sequence for preparing 1,3-cyclopentadiene from cyclopentane.

Provide the major organic product of the following reaction.

How many molecular orbitals are needed to represent the conjugated pi system of β-carotene?

Draw the LUMO of pentadienyl anion.

Predict the outcome of the reaction shown below.

What diene and dienophile would react to give the product below?

In the allyl radical, which π molecular orbital is singly occupied?

Give a representation of the lowest occupied π MO of 1,3-butadiene in its ground state.

What is the major organic product which results when cycloheptene is irradiated in the presence of N-bromosuccinimide?

How many electrons populate the π molecular orbitals of the allyl radical?

What diene and dienophile are used in the Diels-Alder route to the compound shown?

Draw the resonance structures of the intermediate and then predict the two major products in the following reaction and label them as a kinetic or thermodynamic product.

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

What diene and dienophile would react to give the product below?

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

What descriptive term is applied to the type of diene represented by 1,5-octadiene?

Draw the LUMO of 1,3-butadiene.

Which of the following compounds absorbs the longest wavelength of UV-visible light?

When 3-bromobut-1-ene is heated in a good ionizing solvent, reactions occur through a carbocation intermediate. Draw all reasonable resonance contributors of this cation and indicate which is the major contributor.

Provide the two major organic products of the following reaction.