SAMPLE EXAM

Question 1:

Part A: 2,4-Dimethylglutaric acid is a component of inhibitor of the angiotensin-converting enzyme(ACE), pentopril. Is this compound chiral? Why? Why not?

Part B: In the synthesis of pentopril from the above dicarboxylic acid, one of the carboxylic group is converted into an amide. Would conversion of one carboxylate give a different product than the conversion of the other one? Why?

Part C: Define stereochemical descriptors(R,S) for racemic 2,4-dimethylglutaric acid.

Question 2:

Assign configurations(R, S descriptors and cis/trans geometry) in the enantiomer of H-1 antihistamine agent levocabastine, show below.

Question 3:

Mark(encircle) chemical residues of higher precedence in the following pairs according to Cahn-Ingold-Prelog rules:

Question 4:

Determine the relationship between the two compounds below whether they are:

Superimpossable without bond rotation
Diastereomers
Enantiomers
Conformers

Question 5

Part A: Draw an approximate energy profile for 1,2-dibromoethane molecule as a function of the torsion angle about the C-C bond.

Part B: Label the graph with the Newman projections of conformers corresponding to energy minima and maxima.

Note: You need not to know numerical values of energy differences between conformers to draw the graph.