Diazoketone

Diazoketone is an organic compound that contains both a ketone functional group and a diazo substituent (–N₂). The diazo group is characterized by a nitrogen-nitrogen double bond that can act as a weak electrophile and a good leaving group. Diazo ketones are typically synthesized by the treatment of ketones with diazomethane or with diazoacetic acid derivatives under acidic or basic conditions. A common laboratory preparation involves the condensation of a ketone with tosylhydrazone, followed by dehydrative diazo transfer using a hypervalent iodine reagent. The resulting diazo ketones are often stable enough for isolation but are highly reactive because the diazo group can undergo nitrogen extrusion to generate highly electrophilic carbenes or metal-coordinated carbenes when catalyzed by transition metals.

Because the carbene generated from a diazo ketone is highly versatile, these reagents are used in a variety of transformations, including cyclopropanation, C–H insertion, olefin cyclopropanation, and inter- and intramolecular heteroatom transfer reactions. In medicinal chemistry, diazo ketones have been exploited as precursors for the synthesis of nitrogen-containing heterocycles that may possess pharmacological activity. The reactivity of diazo ketones also makes them valuable intermediates in the synthesis of natural product analogs and in the preparation of compounds with strained ring systems.

Safety data indicate that diazo ketones are potentially toxic and can be explosive if concentrated or improperly handled. They should be stored at low temperatures, in small quantities, and under an inert atmosphere. Proper personal protective equipment and ventilation are mandatory during manipulation. The hazardous nature of the diazo functional group, combined with the electrophilic ketone, demands careful experimental design and respect for standard safety protocols.