CH3 NH3, H* H3C H3C CH `N' Substituted pyrroles are often prepared by treatment of a 1,4-diketone with ammonia in the presence of catalytic H*. The mechanism involves the following steps: 1) Protonation of the carbonyl oxygen and nucleophilic attack by ammonia form tetrahedral intermediate 1; 2) Proton transfer leads to protonated carbinolamine 2; 3) B-elimination leads to enamine 3; 4) Protonation of the carbonyl oxygen and nucleophilic attack by the amine form tetrahedral intermediate 4; 5) Proton transfer leads to protonated carbinolamine 5; 6) B-elimination leads to the final product. Write out the reaction mechanism on a separate sheet of paper, and then draw the structure of tetrahedral intermediate 4. You do not have to consider stereochemistry. • You do not have to explicitly draw H atoms. • Do not include lone pairs in your answer.

CH3 NH3, H* H3C H3C CH `N' Substituted pyrroles are often prepared by treatment of a 1,4-diketone with ammonia in the presence of catalytic H*. The mechanism involves the following steps: 1) Protonation of the carbonyl oxygen and nucleophilic attack by ammonia form tetrahedral intermediate 1; 2) Proton transfer leads to protonated carbinolamine 2; 3) B-elimination leads to enamine 3; 4) Protonation of the carbonyl oxygen and nucleophilic attack by the amine form tetrahedral intermediate 4; 5) Proton transfer leads to protonated carbinolamine 5; 6) B-elimination leads to the final product. Write out the reaction mechanism on a separate sheet of paper, and then draw the structure of tetrahedral intermediate 4. You do not have to consider stereochemistry. • You do not have to explicitly draw H atoms. • Do not include lone pairs in your answer.

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter18: Functional Derivatives Of Carboxylic Acids

Section: Chapter Questions

Problem 18.38P: A step in a synthesis of PGE1 (prostaglandin E1, alprostadil) is the reaction of a trisubstituted...

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