Diazo Ketone Reactions

The Arndt-Eistert reaction is a special case of a more general class of diazo ketone reactions. If we assume that diazo ketones normally decompose to acyl carbenes, then numerous subsequent reactions can be imagined, and many have been realized. The following diagram outlines some of these transformations, originating from the diazo ketone formula in the center of the diagram. Molecular nitrogen is lost in each case, and the Wolff rearrangement path is on the left. Most of the other reactions reflect the ability of carbenes to insert into sigma bonds or add to double bonds. Metal catalysts are sometimes used to facilitate certain reactions, and may associate with carbenes to generate carbenoid intermediates.