Used as a key reagent in organic synthesis, particularly in cyclopropanation reactions via metal-catalyzed decomposition. It serves as a diazo compound that transfers carbene intermediates to alkenes, enabling the formation of cyclopropane rings, which are important structural motifs in pharmaceuticals and agrochemicals. Commonly employed in rhodium- or copper-catalyzed reactions to build complex molecular architectures. Also utilized in X-H insertion reactions (such as C–H, O–H, or N–H insertions) to form new carbon-heteroatom bonds. Its phenyl and ester groups help stabilize the diazo compound while allowing further functionalization of the product. Widely applied in the synthesis of natural products and bioactive molecules.