Methyl phenyldiazoacetate is the organic compound with the formula C<sub>6</sub>H<sub>5</sub>C(N<sub>2</sub>)CO<sub>2</sub>Me. It is a diazo derivative of methyl phenylacetate. Colloquially referred to as "phenyldiazoacetate", it is generated and used in situ after isolation as a yellow oil.
Methyl phenyldiazoacetate and many related derivatives are precursors to donor-acceptor carbenes, which can be used for cyclopropanation or to insert into C-H bonds of organic substrates. These reactions are catalyzed by dirhodium tetraacetate or related chiral complexes. Methyl phenyldiazoacetate is prepared by treating methyl phenylacetate with p-acetamidobenzenesulfonyl azide in the presence of base.