vi Contents 4.3 Pyran-2-ones(a-Pyrones) 61 44 45 Pyran-4-ones(-Pyrones Reduced Pyrans 5 4.6 Saccharides and Carbohydrates 65 Benzopyrylium Salts,Coumarins, Chrom n es,Flavonoids and Related Compounds 68 51 Structural Types and Nomenclature 5.2 Coumarins 5.3 Chromones(Benzopyran-4-ones) 80D 6 Five-membered Heterocycles containing One Heteroatom:Pyrrole,Furan and Thiophene 77 6.1 Pyrrole 6.2 Furan 6.3 Thiophene 91 Benzo[b]pyrrole,Benzo[b]furan and Benzo[b]thiophene 97 7.1 Indole(Benzo[blpyrrole) 7.2 Benzo[b]furan and Benzo[b]thiophene 110 8 Four-membered Heterocycles containing a Single Nitrogen,Oxygen or Sulfur Atom 115 Azete,Azetine and Azetidine 115 Oxetene and Oxetane 121 8.3 Thietene and Thietane 122 Answers to Problems 125 Subject Index 141 vi Contents 4.3 Pyran-2-ones (a-Pyrones) 4.4 Pyran-4-ones (y-Pyrones) 4.5 Reduced Pyrans 4.6 Saccharides and Carbohydrates 61 63 65 65 5 Benropyrylium Salts, Coumarins, Chromones, Flavonoids and Related Compounds 68 5.1 Structural Types and Nomenclature 5.2 Coumarins 5.3 Chromones (Benzopyran-4-ones) 68 70 72 6 Five-membered Heterocycles containing One Heteroatom: Pyrrole, Furan and Thiophene 77 6.1 Pyrrole 6.2 Furan 6.3 Thiophene 77 85 91 7 Benzo[b]pyrrole, Benzo[b]furan and Benzo[&]thiophene 97 7.1 Indole (Benzo[b]pyrrole) 7.2 Benzo[b]furan and Benzo[b]thiophene 97 110 8 Four-membered Heterocycles containing a Single Nitrogen, Oxygen or Sulfur Atom 115 8.1 Azete, Azetine and Azetidine 8.2 Oxetene and Oxetane 8.3 Thietene and Thietane 115 121 122 Answers to Problems 125 Subject Index 141