text: Aldehyde substituents suffer nucleophilic addition in the presence of organolithium compounds; however, adducts of aldehydes with lithium diamines can serve as effective directing groups for lateral lithiation. Subsequent treatment with an electrophilic primary alkyl halide and elimination of the diamine provides functionalized aryl aldehydes.
  Tertiary amides are highly effective directing groups. After treatment of the resulting benzylic anion with an aldehyde, cyclization leads to lactones. Carboxamides, in which the amide is attached to the aromatic ring through nitrogen rather than carbon, are also effective directing groups.
  Related O-aryl carbamates are good directing groups; upon warming, the resulting organolithiums undergo rearrangement to benzylic amides (the Snieckus-Fries rearrangement) via migration of the carbonyl carbon from oxygen to carbon. 
  Secondary N-aryl carbamates (along with secondary amides, ketones, and other directing groups containing acidic hydrogens) must be treated with two equivalents of organolithium reagent for lateral lithiation to occur. In the case below, sec-butyllithium is used to avoid competitive addition to the Boc group.
  Sulfonamides require two equivalents of an organolithium reagent for lateral lithiation, but represent a useful class of directing groups. Treatment with ketones leads to tertiary alcohols in high yield.