40 Heterocyclic compounds -basic structures-makes medicinal chemistry easy for you

1. BY
Kencha swathi
Assistant professor
Bangalore
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2. Introduction
 Chemistry is the branch of science which deals with chemical
compounds.
Chemical compounds
Organic compounds Inorganic compounds
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3. Organic compounds
Unbranched
Aromatic compounds Aliphatic compounds
Branched
Homocyclic compounds Heterocyclic compounds
Eg:Cyclohexane ,Cyclobutane Eg: Pyrrole,Pyridine
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4. Heterocyclic Chemistry
 Chemistry which deals with heterocyclic compounds.
 Heterocyclic compounds: Compounds containing Hetero
atoms like N,O,S,P,Si etc.., in the structure along with carbon
and hydrogen atoms are called as heterocyclic compounds.
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5. Nomenclature
According to IUPAC ,prefix and suffix names are as follows:
PREFIX:
Note:Some exceptions are there in the nomenclature
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Name of the heterocyclic atom prefix
Nitrogen Pyr/Aza/Azo
Oxygen Oxa/Oxo
Sulphur Thia/Thio

6. SUFFIX:
If the heterocyclic compound is five membered with two
double bonds then suffix is “OLE”.
If it is five membered heterocyclic compound with one double
bond then suffix is “oline” .
If five membered ring contains no double bonds(completely
saturated) then suffix is “olidine”.
For Six membered ring suffix is “INE”.
For seven membered ring the suffix is “epine”
For eight membered ring the suffix is ocine.
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7. (Pyrrole/Azole) (Pyrroline) (Pyrrolidine)
(Pyridine) (Azepine) (Azocine)
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8. ORDER OF PRIORITY
 If the heterocyclic ring contains two or more different
heteroatoms then the order of priority is
O › S › N › other heteroatoms
 If two or more same heteroatoms are present then saturated
hetero atom gets least possible number.
(Thiazole) (Oxazole) (Imidazole)
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H
1
2
3
1
2
3

9. Name of the
Heterocyclic comp Structure Drug and its use
Aziridine Mitomycin
(Anticancer)
β-lactam Penicillins
(4-azetidinone) &Cephalosporins
Pyrrole Pilocarpine
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10. Furan/oxole Furosemide
Thiophene/Thiole Cephalothin
Pyrroline Succinimide
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11. Pyrrolidine Ethosuximide
Indole/ Indomethacin
Benzopyrrole
Pyrazole Sulphaphenazole
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12. Pyrazoline Analgin
Pyrazolidine Oxyphenbutazone
Imidazole Metronidazole
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13. Oxazole Sulphoxazole
Isoxazole Sulphisoxazole
Thiazole Thiamine
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14. Imidazolidine Ethotoin
Imidazolidine
-2,4-dione phenytoin
(Hydantoin)
Benzimidazole Mebendazole
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15. Tetrazole No drug
Penam Penicillins
Cepham Cephalosporins
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16. Pyridine Isoniazid
Piperidine Pethidine
Pyridazine Sulphonamide
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17. Pyrimidine
Trimethoprim
Pyrimidine-2,4,6-trione
(Barbiturates) Phenobarbitone
Pyrazine Pyrazinamide
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18. Piperazine Prochlorperazine
Quinoline
(Benzopyridine) Chloroquine
Isoquinoline Papaverine
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19. Azepine Carbamazepine
Benzodiazepine Diazepam
Dibenzoazepine Imipramine
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20. Acridine Mepacrine
Phenothiazine Chlorpromazine
Phenazine Clofazimine
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21. Thiadiazole Acetazolamide
Purine Mercaptopurine
Pteridine Folic acid
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22. Xanthine Caffeine
Octahydroazocine Guanethidine
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