ABSTRACT
Synthesis is one of the ultimate challenges in organic chemistry. The developments and discoveries of each generation build upon each other so that synthetic targets of ever increasing complexity become possible. The importance of synthesis drives the need for new reactions. Some of the syntheses reported in this chapter are landmark achievements and the reader should consult a selection of the original papers referred to. The molecule contains seven asymmetric carbon atoms, so that a satisfactory synthesis requires the application of stereoselective procedures. Chloramphenicol is a broad-spectrum antibiotic, isolated from cultures of the soil bacteria Streptomyces venezuelae and from the moon snail Lunatia heros. The following are two syntheses; the former gives a racemic mixture, and the latter is a modern asymmetric synthesis of the active d-threo diastereomer. The challenge in the synthesis of codeine is the presence of five contiguous chiral centres, four of which define ring junctions.
