synthesis of Drugs

SEC1T: Pharmaceutical Chemistry 2019
DR. S DEY : STUDY MATERIAL : PAPER - SEC1T Page 1
Pharmaceutical Chemistry
Dr. Satyajit Dey
Basic Retro-synthetic approach & Synthesis of Drugs
Analgesic, antipyretic & anti-inflammatory drugs:
Aspirin:
Acetyl salicylic acid, commonly known as Aspirin, possesses analgesic, antipyretic & anti-
inflammatory properties.
Retro-synthesis:
Synthesis:
Method I:
Method II:

Side effects: The most common side effects of aspirin involve the gastrointestinal system.
Gastrointestinal side effects are indigestion, ulcerations, abdominal burning, pain, cramping, nausea,
gastritis, and even serious gastrointestinal bleeding and liver toxicity.
Paracetamol:
Acetaminophen (or Paracetamol) is a well-known drug that is used to relieve headaches, fever, and
aches and pains in joints and muscles. It is also a main ingredient in many cold and flu
medications and prescriptions. It is considered a safe and effective drug when used in the
recommended dosages.
Retro-synthesis I:
Synthesis:
Retro-synthesis II:
Synthesis:

Side effects:
The following allergic reaction may occur on consumption of paracetamol: hives; difficulty breathing;
swelling of your face, lips, tongue, or throat. Other side effects may include low fever with nausea,
stomach pain, and loss of appetite, dark urine, clay-colored stools or rjaundice (yellowing of the skin
or eyes).
Ibuprofen:
Synthesis of

METHOD II: Traditional Synthesis involving less than 40 % atom utilization.
METHOD III: A Greener Synthesis of Ibuprofen: Involves more than 80 % atom
utilization
METHOD IV: Starting from isobutyl benzene

METHOD V: Starting from Styrene
Medicinal use of Ibuprofen:
It is used to relief pain and to reduce fever. It is a non-steroidal anti-inflammatory drug.
Side effects:
Antibiotics:
Chloramphenicol: It is capable of exerting its effect against viral diseases as well as those
due to bacterial invasion and opens up the whole field of the chemotherapy of virus and rickettsial
infections in man including typhus, undulant fever, Salmonella septicaemia, whooping cough,
gastroenteritis, lymphogranulomainguinale, typhoid and paratyphoid.
Chloramphenicol is particularly recommended for the management and treatment of serious
infections produced by the strains of both Gram-positive and Gram-negative organism thathave
developedeventually resistance to either ampicillin or penicillin G, for instance: H. influenzae,
Salmonella typhi, S. pneumoniae, B. fragilis, and N. meningitidis.
Structure Activity Relationship:
Chloramphenicol possesses two chiral (asymmetric) carbon atomsas shown below:

It has been observed that the biological activity resides almost exclusively in the ‘D-Threoisomer’
whereas the L-Threo, and D- and L-Erythroisomers are virtually inactive.
Retro-Synthesis:
Synthesis:

Anti-bacterial & Anti-fungal Drugs:
A. Sulpha Drugs: Since some dyestuffs selectively stained micro-organisms and shows the anti-
bacterial activity. Prontosil red was active against a Streptococcus infection in mice and a
Staphylococcus infection in rabbits. The compound was rapidly tested in humans where it was
shown to control septicaemia in children including Domagk’s daughter. It had a significant effect on
infant mortality. It was seen that the active compound was a bio-transformation product,
sulfanilamide. However, although this was used as an anti-bacterial agent, it was accompanied by a
side effect. The amino group was acetylated in man and the acetate crystallized out in the kidneys. A
series of structural modifications were then made to overcome this problem.
Sulphacetamide:
Retro-synthesis:

Synthesis:
Medicinal use of Sulphacetamide:
It is chiefly employed by local application in injuries or infections of the eyes. It is also used in the
treatment of acute conjunctivitis and in the prophylaxis of ocular infections after injuries or burns.
Sulphamethoxazole:
Retro-synthesis:
Synthesis:

Synthesis of 5-Methylisoxazole-3-amine:
Alternative Method of Synthesis of 5-Methylisoxazole-3-amine:
Medicinal use of sulphamethoxazole:
Combined with phenazopyridine, it is used to treat urinary tract infections and to reduce pain
associated with it. Combined with trimethoprim, it is used to treat urinary tract infections and ear
infections, bronchitis, gonorrhoea etc.

B. Pyrimidine Analogue:
Trimethoprim:
Retro-synthesis:
Synthesis:

Medicinal use of trimethoprim:
It has been employed in conjunction with sulfametopyrazine in the treatment of chloroquine-
resistant malaria but unfortunately could not attain wide acceptance. It is used in conjunction with
sulphonamides in the treatment of bacterial infections viz., trimethoprim with sulphamethoxazole.
Anti-laprosy Drugs:
Sulfone Analogue: Dapsone:
Retro-synthesis:
Synthesis:
Medicinal use of Dapsone:
It is employed profusely in the treatment of both lepromatous and tuberculoid types of leprosy.
Dapsone in conjunction with other agents has also been effectively used in the treatment of malaria
due to chloroquine resistant P. falciparum.
Anti-viral Drugs:

Anti-viral drugs exert their effect against DNA viruses either by interfering with their replication due
to its similarity of structure to the nucleotide structures in natural DNA virus or by interfering with
the nucleic acid replication of the virus, specifically inhibiting the early steps in DNA synthesis.
Acyclovir:
Retro-synthesis:
Synthesis:
Medicinal use of Acyclovir:
Acyclovir was the first effective antiviral drug. It is effective against a number of herpes viruses,
notably simplex, varicella-zoster (shingles), varicella (chickenpox) and Epstein-Barr virus (glandular
fever).
Central Nervous system Drug:

Phenobarbital:
Retro-synthesis:
Synthesis:
Medicinal use of Phenobarbital:
Phenobarbital is used as both sedative and hypnotic.
Diazepam:
Method I: Retro-synthesis:

Synthesis:
Method II: Retro-synthesis
Synthesis:

Medicinal use of Diazepam:
It is used as an anti-anxiety and anti-tension drug.
Side effects:
The more common side effects that occur with diazepam include: drowsiness, tiredness or fatigue,
muscle weakness, inability to control muscle movements (ataxia), headache, tremor, dizziness, dry
mouth or excessive saliva, nausea and constipation.
Cardiovascular Drug:
Glyceryl trinitrate:
Retro-synthesis:
Synthesis:
Medicinal use of Glyceryl trinitrate:
In medicine, Trinitrate (also called nitroglycerin) is used for angina, a painful symptom of ischemic
heart disease caused by inadequate flow of blood and oxygen to the heart caused due to the
narrowing of blood vessels that carries blood to the heart muscle and as a potent antihypertensive
agent. Nitroglycerin corrects the imbalance between the flow of oxygen and blood to the heart.
Side effects:
Headache, Flushing or redness of the skin, Dizziness, Weakness or fainting, Rapid heartbeat, Nausea
and vomiting are the very common side effects reported.
Zidovudine (AZT):
Retro-synthesis:

Synthesis:
Medicinal use of Zidovudine:
Zidovudine or AZT is an analog of thymidine that possesses antiviral activity. It is active against the
retroviruses that cause AIDS (HIV virus) and certain types of leukaemia.
Side effects:
Common side effects that have been reported include headaches, nausea, vomiting, insomnia,
tiredness, muscle pain, and loss of appetite. AZT can be toxic to the bone marrow-causing anemia
(lowered red blood cell levels) and neutropenia (lowered neutrophil or white blood cell counts).
Sample Questions:
Q.1 Draw the structure of ibuprofen. Show its retrosynthetic analysis & forward synthesis
Q.2 Identify the A to C in the following reaction scheme. Name the drug & mention its medicinal use.
Q.3 Draw the structure of Phenobarbital. Show its retrosynthetic analysis & forward synthesis.
Q.4 Identify the A to C in the following reaction scheme. Name the drug & mention its medicinal use.

Q.5 Name two potent drugs and discuss the synthesis of one compound.
Q.6 Draw the structure of Phenobarbital. Show its retrosynthetic analysis & forward synthesis.
Q.7 Give the medicinal use of sulphonamides drug with an example.
Q.8 Draw the structure of Phenobarbital. Show its retrosynthetic analysis & forward synthesis
Q.9 Write the chemical name of Paracetamol and Dapsone.
Q.10 Draw the stereo-chemical structure of:
i) Chloramphenicol antibiotic and, ii) Phenobarbital
Q.11 Write down the medicinal uses of Aspirin.
Q.12 Using styrene as the starting compound show the synthesis proposal of Ibuprofen.
Q.13 Show the Green method of synthesis of Ibuprofen.
Q.14 Match the two columns:
Q.15 Identify the Structures of the intermediate compounds A to E in synthesis of chloramphenicol
antibiotic.
Q.16 Write down the procedure for the synthesis of Paracetamol. What is the side effect of AZT-
Zidovudine?
Q.17 Draw the retro-synthetic analysis and forward synthesis of Acyclovir (antiviral agent).

******END*****

synthesis of Drugs

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synthesis of Drugs