Question

Hantzsch pyridine synthesis involves several steps. Some of those are

• A. Aldol reaction
• B. Darzens reaction
• C. Mannich reaction
• D. Michael addition

Hint:

Hantzsch pyridine synthesis is a multicomponent reaction that combines condensation (Mannich) and conjugate addition (Michael) steps to form a dihydropyridine ring.

Answer 1

The Correct Option is A, D

Step 1: Recall the Hantzsch pyridine synthesis.
Hantzsch pyridine synthesis involves the condensation of an aldehyde, a β-keto ester, and ammonia (or ammonium acetate) to form a substituted dihydropyridine, which on oxidation gives a pyridine derivative.
Step 2: Identify the key steps.
- The reaction involves a Mannich-type condensation between an aldehyde and β-keto ester in the presence of ammonia.
- A subsequent Michael addition occurs between an enamine and an α,β-unsaturated carbonyl intermediate.
- Aldol or Darzens reactions are not part of the mechanism.
Step 3: Conclusion.
The correct processes involved are Mannich reaction and Michael addition.