Question

Draw a full mechanism for the formation of the dihydropyridine structure from a generic aldehyde!

Answer 1

Solution:

Two moles of -ketoesters (Substituted) reacts with one mole of aldehyde and ammonia forms substituted dihydropyridine carboxylate (B). B on hydrolysis and decarboxylation yields substituted dihydropyridine (A). In this reaction , intermediate (I₁) - Knoevenagal condensation reaction and (I₂) - condensation reaction, are independently prepared and reacted in the subsequent step.

The reaction scheme and mechanism from (I₁) + (I₂) to (B)  are given below.