Chapter 5, Problem 39P

(a)

Interpretation Introduction

Interpretation:The stereocenter in thalidomide should be identified.

  

Concept introduction:Chiral carbon is any stereocenter attached to four different alkyl substituents. It is also known as stereocenter. If any two of the substituent happen to be similar the center is regarded as achiral. However, the most essential criteria that help to distinguish a chiral or non-chiral system ispresence of any symmetry element. If any plane center or axis of symmetry is identified it makes molecule achiral and optically inactive.

Thalidomide was originally taken as sedative against morning sickness; while one of its enantiomers was successful as sedative, other enantiomer caused certain birth defects.

(b)

Interpretation Introduction

Interpretation:Two enantiomers in thalidomide should be drawn and labeled.

  

Concept introduction:In order to assign absolute configuration of R and S, Cahn − Ingold − Prelog rules are used and the first step is to assign the priority order on the basis of atomic number. The one with highest atomic number gest highest priority and is designated as a and so on.

The Fischer projection is written along with the priorities assigned and groups are interchanged between adjacent places so as to obtain lowest priority group at the bottom or lowest priority.

If the groups now are arranged are read from highest towards least in clockwise fashion the R is assigned to the stereocenter, if the rotation is anticlockwise the S is assigned at the configuration.

(c)

Interpretation Introduction

Interpretation: The relevant hydrogen that shows acidic properties should be identified in thalidomide.

  

Concept introduction:Thalidomide was originally taken as sedative against morning sickness; while one of its enantiomer was successful as sedative, other enantiomer caused certain birth defects. The two enantiomers of thalidomide are as follows: