Selectivity I: Chemoselectivity and protecting groups

This chapter evaluates chemoselectivity and protecting groups. In a chemoselective reaction, one functional group within the molecule reacts, leaving further potentially reactive functionality unaffected. Many of the principal transformations involved in functional group interconversions (FGIs) were introduced in the third chapter of this text. The reactions may involve addition, substitution, elimination, reduction, and oxidation. There are now a plethora of mild and selective reagents available to effect specific transformations. As a general rule, when there are two functional groups of unequal reactivity within a molecule, the more reactive can be made to react alone. However, it may not be possible to react the less reactive functional group selectively.