(C) for Each of the Following Phrases, Indicate Whether It S a Characteristic of EAS, NAS

Spring 2008

Workshop #6

Problem #1:

CHOICES

(a) Circle the most acidic hydrogen in each structure and then rank them from STRONGEST to WEAKEST acid. Briefly explain to the group why you ranked them as you did.

(b) Rank the following in DECREASING order of basicity.

(c) For each of the following phrases, indicate whether it’s a characteristic of EAS, NAS, or BOTH.

____ Must be an electron-withdrawing group ortho or para to the leaving group

____ Involves a carbocation intermediate that is resonance stabilized

____ An electron-donating group on the ring activates the positions ortho and para to it

____ No leaving group is required

____ Stages of addition and elimination lead ultimately to overall substitution

____ Involves a carbanion intermediate that is resonance stabilized

____ The ring acts as the nucleophile and reacts with a reagent electrophile

____ Must be a leaving group on the ring (usually a halogen)

____ A strong electron-withdrawing group on the ring deactivates the ortho and para positions leading to substitution at the meta position

____ The ring acts as an electrophile and reacts with a reagent nucleophile

(d) For each series of substituted benzenes shown below, indicate:

1.  The one that would be the MOST reactive in EAS.

2.  The one that would be the LEAST reactive in EAS.

3.  The one that would give the highest percentage of meta product.

(e) For each of the following compounds, use the descriptions OK NAS, GREAT NAS, OK EAS, GREAT EAS, or NEITHER to describe the likely reaction pathway.

(f) Which of the following would not be suitable for use as an electrophile in a reaction involving a Grignard or organolithium reagent?

Problem #2:

Complete the following reactions by drawing the structure(s) of the product(s) realizing that they are all under KINETIC control (this means that electronic effects outweigh steric effects).

Problem #3:

Propose a mechanism for the following reaction.

Problem #4:

Celestolide, a perfuming agent with a musk odor, is prepared by the following sequence of reactions.

·  Give the mechanism for both reactions using the curved-arrow method.

·  Draw the structure of celestolide and rationalize its structure by critical examination of your proposed reaction mechanism.

·  What would be the product of the reaction of celestolide with H2NNH2 in NaOH (aq)?

Problem #5:

Propose syntheses of the following target molecules starting with benzene.