1. PYRROLE
Occurs in coal tar. Colourless liquid with odour of chloroform, mp -24C, bp 131C, slightly soluble in water. It has resonance energy of 100KJ per mole. It is found in proline and nicotine.

2. RETROSYNTHESIS OF PYRROLE

3. Acid-base rxns of pyrrole
Protonation occurs at C-2

4. Electrophilic substitution rxns

7. COMPOUNDS CONTAINING PYRROLE OR PYRR
OLIDINE

8. IMIDAZOLE

9. RETROSYNTHESIS OF IMIDAZOLE

11. COMPOUNDS CONTAINING IMIDAZOLE

12. PYRAZOLE CONT’D

13. PYRAZOLE CONT’D

14. RETROSYNTHESIS OF OXAZOLE

15. OXAZOLE CONT’D

16. OXAZOLE CONT’D
OXAZOLE IS COLOURLESS LIQ, SMELLS LIKE PYRIDINE, SOL, IN WATER, ARYL-SUBSTITUTED STRONGLY FLUORESCENT. SUITABLE AS LUMINOUS SUBSTANCES (LIQ SCINTILLATION COUNTERS OR USED AS BRIGHTENING AGENTS)

17. SUMMARY-RXNS

18. 1,3-benzoxazole
Colourless liq, sol. In water. Aroma constituent in cocoa, coconuts, walnuts and beer. Derivative occurs in fireflies.

19. Colourless crystals, moderately sol in water, very soluble in ethanol

20. BENZO[b]THIPHENE
Benzo[b]thiophene occurs in coal tar and roasted coffee beans

21. Derivative used as antibacterial drug(with nitrophenyl side chain), colourless, oily liq, water insoluble, occurs in coal tar

23. Colourless, fluorescent crystals,occurs in coal tar

24. Electro subs occurs at C-3. Colourless solid leaflet crystals, mod
Electro subs occurs at C-3. Colourless solid leaflet crystals, mod. Sol in water. Occurs in coal tar and jasmine oil

25. Bufotein-poison on frog skin; psilocin-causes hallucinations

26. NOMENCLATURE SIX MEMB.

33. PYRILIUM ION
Planar and slightly distorted hexagon. It is aromatic. Positive charge at 2,4,6.Hence nucleophilic attack at 2,4,6

34. RING OPENING
OH adds at pos 2 and with heating ring opens

35. Ring opens to form 1,5-diketone or 1,5-dialdehyde

36. RING OPENING CON’D
Grignard reagent can also add at pos 2. Heating opens up the ring to form dienone

37. 2H-PYRAN
The parent compd has not yet been isolated. However, 2,2-disubstituted derivatives have been isolated

38. THERMAL RING OPENING OF 2H-PYRAN DERIVATIVE
This compd undergoes thermal ring opening

39. 2H-PYRAN-2-ONE
Bp of 208C, colourless liq. It behaves like 1,3-dienes and also like lactones

40. RXN OF 2H-PYRAN-2-ONE

41. SYNTHESIS OF TETRAHYDROPYRAN
Dehydration rxn catalyzed by acid. Loss of water with subsequent cyclization

42. 2H-CHROMENE
It is found in natural products like plants

43. 2H-CHROMEN-2-ONE or coumarin
Occurs in plants (lavender), mp 68C, colourless crystalline solid. Reacts like lactone.

44. LACTONE RING OPENING
Ring opens to form free carboxylic acid

45. 1-BENZOPYRILIUM ION
The derivative of this compd is found in leaves and flowers. It gives various colours to leaves and flowers

46. BENZOPYRILIUM ION CONT’D
Numerous red, blue and violet pigments of blossom and leaves are made of this derivative. Occurs as glycosides(anthocyanins)

47. 4H-PYRAN
Unlike 2H-Pyran, the parent compd is known. It is synthesized from 1,5-diketone or 1,5-dialdehyde

48. SYNTHESIS OF 4H-PYRAN

49. 4H-PYRAN-4-ONE
Mp 32C, colourless, crystalline. Occurs in the bark of larch tree; also formed by dry distillation of starch and cellulose. Also found in opium

50. 4H-1-BENZOPYRAN(4H-CHROMENE)
Derivatives found in plants

51. 4H-CHROMEN-4-ONE(4H-1-BENZOPYRAN-4-ONE)
Mp 59C, colourless needles. Also known as chromone. Derivative found in plants

52. OTHER DERIVATIVES OF 4H-CHROMEN-4-ONE
Phenyl at pos 2 gives FLAVONES, eg apigenin, leteolin. Occurs in yellow pigments in plants

53. FLAVONES CONT’D
Flavones have a wide spectrum of biological activity-anti-tumor, anti-inflammatory. Also used as dyes in textile industry

54. FLAVONES CONT’D
Quercetin found in apples. Major constituent of red wine. Found to reduce incidences of cardiovascular diseases

55. Chroman, flavan, flavanol etc
Constituent of vitamin E

56. Vitamin E

57. Flavan, flavanol

58. DIBENZOPYRAN DERIVATIVES