浙江大学高等有机真题3.pdf

Advanced Organic Chemistry Lecture 3 Xufeng Lin Sep., 2009 2. Stereochemistry Chirality in Tools Helix Chirality in Art L-DOPA Dopamine L-DOPA Prodrug Decarboxylation A tragedy occurred in Europe during the 1950s and early 1960s involving the drug thalidomide. This is a powerful sedative and antinausea agent that was considered especially appropriate for use during early pregnancy. Unfortunately, it was soon found that this drug was a very potent teratogen and thus had serious harmful effects on the fetus. Further study showed that this teratogenicity was caused by the (S)-isomer (which had little sedative effect), but the drug was sold in racemic form. The (R)-isomer (the active sedative) was found not to cause deformities in animals even in high doses. O O HN H Thalidomide O N O If we consider the biological activities of chiral compounds in general, there are four different behaviors: 1) only one enantiomer has the desired biological activity, and the other one does not show signifcant bioactivity; 2) both enantiomers have identical or nearly identical bioactivity; 3) the enantiomers have quantitatively different activity; 4) the two enantiomers have different kinds of biological activity. 天冬酰胺 薄荷 OH O OH O OH O OH OH O OH S-(+)-Alkannin (R)-(-)-Shikonin The toxicity of naturally occurring (-)-nicotine is much greater than that of un