Direct amidation of aldoses and decarboxylative amidation of alpha-keto acids: an efficient conjugation method for

Chia-Ching Cho1, Jia-Nan Liu, Chung-Hsun Chien

  • 1Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.

Related Concept Videos

Conjugate Addition to α,β-Unsaturated Carbonyl Compounds01:09

Conjugate Addition to α,β-Unsaturated Carbonyl Compounds

α,β-Unsaturated carbonyl compounds are molecules bearing a carbonyl and alkene functionality in conjugation with each other. The conjugation in the molecule leads to three resonance structures. The hybrid form exhibits two probable electrophilic sites: the carbonyl carbon and the β carbon.
C–C Bond Formation: Aldol Condensation Overview01:10

C–C Bond Formation: Aldol Condensation Overview

Aldol condensation is an important route in synthetic organic chemistry used to generate a new carbon–carbon bond under basic or acidic conditions. The aldol condensation reaction presented in Figure 1 constitutes an aldol addition reaction followed by the dehydration process.
Crossed Aldol Reaction Using Strong Bases: Directed Aldol Reaction00:56

Crossed Aldol Reaction Using Strong Bases: Directed Aldol Reaction

The reaction between two different carbonyl compounds comprising α hydrogen in the presence of a strong base like lithium diisopropylamide (LDA) to form a crossed aldol product is known as a directed aldol reaction. The directed aldol reaction is depicted in Figure 1.
Acid-Catalyzed Aldol Addition Reaction01:15

Acid-Catalyzed Aldol Addition Reaction

The aldol reaction of a ketone under acidic conditions successfully forms an unsaturated carbonyl as the final product instead of an aldol. The acid-catalyzed aldol reaction is depicted in Figure 1.
Conjugate Addition (1,4-Addition) vs Direct Addition (1,2-Addition)01:27

Conjugate Addition (1,4-Addition) vs Direct Addition (1,2-Addition)

α,β-Unsaturated carbonyl compounds with two electrophilic sites, the carbonyl carbon, and the β carbon, are susceptible to nucleophilic attack via two modes: conjugate or 1,4-addition and direct or 1,2-addition.
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...
Base-Catalyzed Aldol Addition Reaction01:08

Base-Catalyzed Aldol Addition Reaction

As depicted in Figure 1, base-catalyzed aldol addition involves adding two carbonyl compounds in aqueous sodium hydroxide to form a β-hydroxy carbonyl compound.