The Buchner–Curtius–Schlotterbeck reaction is the reaction of aldehydes or ketones with aliphatic diazoalkanes to form homologated ketones. It was first described by Eduard Buchner and Theodor Curtius in 1885  and later by Fritz Schlotterbeck in 1907.  Two German chemists also preceded Schlotterbeck in discovery of the reaction, Hans von Pechmann in 1895 and Viktor Meyer in 1905.   The reaction has since been extended to the synthesis of β-keto esters from the condensation between aldehydes and diazo esters.  The general reaction scheme is as follows:
The reaction yields two possible carbonyl compounds (I and II) along with an epoxide (III).  The ratio of the products is determined by the reactant used and the reaction conditions.