Synthesis of Cyclobutenediones and Anhydrides from Alkynes Using the Fe(CO)₅/Me₃NO Reagent System

Abstract

Coordinatively unsaturated “Fe(CO)4” species prepared using inexpensive Me3NO and Fe(CO)5 reacts with alkynes under ambient conditions to give cyclobutenediones in moderate to good yields (50−75%) after CuCl2·2H2O oxidation. The corresponding cyclic anhydrides are obtained in 60−80% yields when an excess of the amine oxide was used.