Thalidomide-How stereoisomers can have complete different properties

Thalidomide was once prescribed in Europe as a sedative and anti-nausea agent for pregnant women. The molecule contains one stereogenic center thus, it exists as a pair of enantiomers. Despite the beneficial sedative properties of the (R)-enantiomer, the (S)-enantiomer, unfortunately, had a catastrophic effect and thousands of children were born with severe defects.Due to the diligence of an FDA medical officer Frances Oldhan Kelsey, thalidomide was never allowed to enter the United States market.

Learn how to distinguish between enantiomers and other isomers in Stereochemistry section as it is common for them to have different properties and biological activities.