17.1 Product Class 1: Six-Membered Hetarenes with Two Unlike Heteroatoms
17.1.1 Product Subclass 1: Two Unlike Oxygen, Sulfur, Selenium, or Tellurium Atoms
17.1.2 Product Subclass 2: One Oxygen and One Nitrogen or Phosphorus Atom
17.1.3 Product Subclass 3: One Sulfur, Selenium, or Tellurium Atom and One Nitrogen or Phosphorus Atom
17.2 Product Class 2: Six-Membered Hetarenes with Three Heteroatoms
17.2.1 Product Subclass 1: 1,2,3-Triazines and Phosphorus Analogues
17.2.2 Product Subclass 2: 1,2,4-Triazines
17.2.3 Product Subclass 3: 1,3,5-Triazines and Phosphorus Analogues
17.3 Product Class 3: Six-Membered Hetarenes with More Than Three Heteroatoms
17.4 Product Class 4: Seven-Membered Hetarenes with One Heteroatom
17.4.1 Product Subclass 1: Oxepins
17.4.2 Product Subclass 2: Benzoxepins
17.4.3 Product Subclass 3: Thiepins and Selenium Analogues
17.4.4 Product Subclass 4: Benzothiepins and Selenium/Tellurium Analogues
17.4.5 Product Subclass 5: Azepines, Cyclopentazepines, and Phosphorus Analogues
17.4.6 Product Subclass 6: Benzazepines and Their Group 15 Analogues
17.5 Product Class 5: Seven-Membered Hetarenes with Two or More Heteroatoms
17.6 Product Class 6: Eight- and Nine-Membered Hetarenes and Heteroannulenes with One or More Heteroatoms
17.7 Product Class 7: Cyclazines
17.8 Product Class 8: Porphyrins and Related Compounds
17.9 Product Class 9: Phthalocyanines and Related Compounds
