The first chapter by Aaron Wrobleski, Thomas C. Coombs, Chan Woo Huh, Sze-Wan Li and Jeffrey Aubé features a classic chemical reaction for introducing nitrogen into organic compounds, namely the Schmidt Reaction. This venerable reaction usually involves the combination of hydrazoic acid with aldehydes or ketones to generate amides. In fact The Schmidt Reaction was the subject of a previous chapter in Organic Reactions in Volume 3. Obviously, many new developments have appeared since 1946 and among the most synthetically useful are the reactions of alkyl azides with carbonyl compounds extensively developed in the Aubé laboratories.

The second chapter by William F. Berkowitz shines a spotlight on a less-well-known, though no less fascinating transformation that introduces nitrogen into organic compounds, The Neber Rearrangement. This unique chemical reaction also begins with ketones but provides the precious nitrogen atom, not from azide, but in the form of hydroxylamine that creates an oxime derivative.

The third chapter by Lynn James Guziec and Frank S. Guziec, Jr. describes an unusual class of reactions that involve the loss of small molecular fragments from a ring in service of uniting separate carbon atoms in that ring to form alkenes. These so called "extrusion reactions" are more commonly known for the loss of a single molecular fragment as in, e.g. the Ramburg-Bäcklund Reaction which has been reviewed twice in this series (L. Paquette, Volume 25 and R. J. K. Taylor and G. Casy, Volume 62). However, the chapter in this volume outranks the other extrusions in that two separate molecular fragments are lost with the formation of two new carbon-carbon bonds (twofold extrusion reactions).