Question

A) Select the configuration of the pharmacologically active enantiomer that stops a headache B) Is the active ingredient in ibuprofen, shown in blue, the R or S enantiomer? C) Is the anti-nausea enantiomer on the left shown in red the R or the S configuration? D) Draw the skeletal structure of the enantiomer of thalidomide on the right shown in blue which causes birth defects. You should NOT add any hydrogen's, these are understood. Make sure the tapered end (the skinny end) of the wedge/dashed bond is bonded to the chiral carbon

Answer 1

A) Answer: (S)-Naproxen

It is commonly used pain reliever drug that acts by binding to cyclooxygenase(enzyme) and inhibits it from synthesizing prostaglandins.Thus, decrease in prostaglandin reduces pain .However,(R)-Naproxen does not bind to cyclooxygenase and is toxic ,specially, to liver.

B) see image

CIP or Cahn-Ingold -Priority rules to be followed in assigning R and S configuration:

-Select the chiral or asymmetric carbon with different groups attached to it.Assign priority based on the atomic number of the first atom in the substituents or groups attached to the chiral carbon.If first atom in the substituent is the same then assign priority on the basis of the second atom along the parent chain of the substituents

-If going from priority group 1-->2---> 3 is clockwise ,and lowest priority is at the back then the configuration is R

--If going from priority group 1-->2---> 3 is Anticlockwise ,and lowest priority is at the back then the configuration is S

-If going from priority group 1-->2---> 3 is clockwise ,and lowest priority is at the front then the configuration is S

-If going from priority group 1-->2---> 3 is Anticlockwise ,and lowest priority is at the front then the configuration is R

C) see image

D) see image

Skeletal structure of a hydrocarbon just shows the line representation of carbon backbone with hetero atoms and the functional groups attached to it.

Answer 2