Peptides may be synthesized using an α-keto acid and a hydroxylamine. Concept introduction: The reaction of formation of an amide/ peptide from an α-keto acid and a hydroxylamine involves an initial nucleophilic substitution of the alkyl group to the keto group followed by decarboxylation and elimination of water molecule. To determine: Mechanism of reaction thought to occur by nucleophilic addition of the N-alkylhydroxylamine to the keto acid as if forming an oxime.

Question

The addition of a nucleophilic group like a thiol (-SH), or an unprotonated amino group (-NH₂) to an a,ß-unsaturated ketone is important for understanding how NAPQI reacts with glutathione, N-acetylcysteine, or protein amino acid side chains containing -SH or -NH2 groups. In this problem we will add mercaptoethanol to p-benzoquinone. p-Benzoquinone will be a simple model of NAPQI. +H H a single uncharged addition product This reaction will proceed in steps. First the H-S-R will add to the unsaturated ketone to give a charged addition product. Next, a simple proton transfer will form an uncharged adduct in which the 6-membered ring contains one carbonyl and a second enolic hydroxyl. The keto form next will tautomerize to its more stable enol form, and in doing so the 6-membered ring becomes aromatic with 6-π electrons. See page 14 of the lecture notes for Lecture 9 How ADME affects preclinical Drug Design February 24, 2023, where I have shown the mechanism for this addition and give the…

Answer 1

Question

Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 26.SE, Problem 28MP

Interpretation Introduction

Interpretation:

Peptides may be synthesized using an α-keto acid and a hydroxylamine.

Concept introduction:

The reaction of formation of an amide/ peptide from an α-keto acid and a hydroxylamine involves an initial nucleophilic substitution of the alkyl group to the keto group followed by decarboxylation and elimination of water molecule.

To determine:

Mechanism of reaction thought to occur by nucleophilic addition of the N-alkylhydroxylamine to the keto acid as if forming an oxime.

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The addition of a nucleophilic group like a thiol (-SH), or an unprotonated amino group (-NH₂) to an a,ß-unsaturated ketone is important for understanding how NAPQI reacts with glutathione, N-acetylcysteine, or protein amino acid side chains containing -SH or -NH2 groups. In this problem we will add mercaptoethanol to p-benzoquinone. p-Benzoquinone will be a simple model of NAPQI. +H H a single uncharged addition product This reaction will proceed in steps. First the H-S-R will add to the unsaturated ketone to give a charged addition product. Next, a simple proton transfer will form an uncharged adduct in which the 6-membered ring contains one carbonyl and a second enolic hydroxyl. The keto form next will tautomerize to its more stable enol form, and in doing so the 6-membered ring becomes aromatic with 6-π electrons. See page 14 of the lecture notes for Lecture 9 How ADME affects preclinical Drug Design February 24, 2023, where I have shown the mechanism for this addition and give the…

4. Here’s a figure-it-out mechanism, resulting in the formation of p-aminophenol from an aromatic hydroxylamine. Would you expect either ortho- or meta-aminophenol to form in competition? Why or why not? H H;0* H -N НО H2O ОН H 5. (a) The triaryl hydroxylamine hydrolyzes in acid to form two products: one compound containing two aromatic rings and one with a single aromatic ring. First, draw the two products and the mechanism of their formation in acidic water (this is another "figure it out" mechanism). Ph H;O* Ph—С—N H,0 Ph ОН (b) Suppose one of the aryl rings had a t-donating group (-OCH3) and the other had a n- withdrawing group (-NO2), both in the para position. Where would the substituents end up in the products (draw them)? Why? Do you suspect this reaction is under kinetic control or thermodynamic control, or both/either?

The following three derivatives of succinimide are anticonvulsants and have found use in the treatment of epilepsy, particularly petit mal seizures. Ph Ph `N' `N' ČH3 ČH3 Methsuximide Ethosuximide Phensuximide Following is a synthesis of phensuximide. CN Ph CN Ph CN 1. NaOH, H2O 2. HC, Н20 NaOEt KCN Ph-CHO cOOEt H cOOEt NC COOEt 3. Нeat Ethyl cyanoacetate (A) (B) Benzaldehyde Ph Ph Ph CH;NH2 НООС СООН Et0oC COOEt `N' (C) (D) ČH3 Phensuximide Methsuximide is formed by a similar pathway to that shown for phensuximide. Draw the structure of the compound that reacts with ethyl cyanoacetate in the synthesis of methsuximide.

Answer 2

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Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 26.SE, Problem 28MP

Interpretation Introduction

Interpretation:

Peptides may be synthesized using an α-keto acid and a hydroxylamine.

Concept introduction:

The reaction of formation of an amide/ peptide from an α-keto acid and a hydroxylamine involves an initial nucleophilic substitution of the alkyl group to the keto group followed by decarboxylation and elimination of water molecule.

To determine:

Mechanism of reaction thought to occur by nucleophilic addition of the N-alkylhydroxylamine to the keto acid as if forming an oxime.

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Answer 3

Question

Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 26.SE, Problem 28MP

Interpretation Introduction

Interpretation:

Peptides may be synthesized using an α-keto acid and a hydroxylamine.

Concept introduction:

The reaction of formation of an amide/ peptide from an α-keto acid and a hydroxylamine involves an initial nucleophilic substitution of the alkyl group to the keto group followed by decarboxylation and elimination of water molecule.

To determine:

Mechanism of reaction thought to occur by nucleophilic addition of the N-alkylhydroxylamine to the keto acid as if forming an oxime.

Expert Solution & Answer

Trending nowThis is a popular solution!

See solution

Check out sample textbook solution

Answer 4

Question

Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 26.SE, Problem 28MP

Interpretation Introduction