Alkaloids Derived by Amination Reactions

Derived from Ornithine
  - Pyrrolidine & Tropane
  - Pyrrolizidine
Derived from Lysine
  - Piperidine
  - Quinolizidine
  - Indolizidine
Derived from Nicotinic Acid
  - Pyridine
Derived from Tyrosine
  - PEA & Simple TIQ
  - Modified BTIQ
  - Phenethylisoquinoline
  - Terpenoid TIQ
  - Amaryllidaceae
Derived from Tryptophan
  - Simple Indole
  - Simple β-Carboline
  - Terpenoid Indole
  - Quinoline
  - Pyrroloindole
  - Ergot
Derived from Anthranilic Acid
  - Quinazoline
  - Quinoline & Acridine
Derived from Histidine
  - Imidazole
Derived by Amination Reactions
  - Acetate-derived
  - Phenylalanine-derived
  - Terpenoid
  - Steroidal
Purine Alkaloids
  - Saxitoxin & Tetrodotoxin

The majority of alkaloids are derived from amino acid precursors by processes that incorporate into the final structure the nitrogen atom together with the amino acid carbon skeleton or a large proportion of it. Many alkaloids do not conform with this description, however, and are synthesized primarily from non-amino acid precursors, with the nitrogen atom being inserted into the structure at a relatively late stage. Such structures are frequently based on terpenoid or steroidal skeletons, though some relatively simple alkaloids also appear to be derived by similar late amination processes. In most of the examples studied, the nitrogen atom is donated from an amino acid source through a transamination reaction with a suitable aldehyde or ketone .