Forming Nitrogen Heterocycles from Aliphatic Amino Acids
How are nitrogen heterocycles formed from aromatic amines? Aliphatic hydrocarbons¹ take a number of forms. The simplest is written CH₃(CH₂)nCH₃, where n is a positive integer.² Replace a hydrogen atom at one end of the chain with a carboxylic acid group (-COOH) and a hydrogen atom at the other end with an amino group (-NH₂), and you have a straight chain amino acid. For instance, choose n = 3. That gives the molecule HOOC-CH₂-CH₂-CH₂-CH₂-NH₂ Its name is 5-aminopentanoic acid or 5-aminovaleric acid. Cyclization Under the right conditions, this species can be cyclized to form an amine salt. The salt is then converted to a cyclic amide, a delta lactam. The lactam is next reduced to the amine piperidine. The overall process is illustrated in Fig. 1. Nitrogen Heterocycles A cyclic…