They can be synthesized from nitriles in sulfuric acid by the Ritter reaction, but their most common mode of synthesis involves reacting an acid chloride with a nitrogen containing compound in base and is called the Schotten-Baumann reaction.
One way of synthesizing these compounds reacts an aryl alkyl ketone with ammonium polysulfide to produce a carboxylic acid and one of these. In addition to the Willgerodt rearrangement, ways of synthesizing cyclic ones include reacting ketones with hydrazoic acid in the Schmidt reaction, or with a cyclic oxime in the Beckmann rearrangement, and that cyclic variety of this functional group is called a (*) lactam. They can be synthesized from nitriles in sulfuric acid by the Ritter reaction, but their most common mode of synthesis involves reacting an acid chloride with a nitrogen containing compound in base and is called the Schotten-Baumann reaction. Even less reactive than esters, these are, FTP, what functional group, a carbonyl bonded to an amine.
One way of synthesizing these compounds reacts an aryl alkyl ketone with ammonium polysulfide to produce a carboxylic acid and one of these.
{amide} (prompt on: carboxylic acid before "carboxylic acid")