Reactive iron carbonyl reagents for conversion of alkynes to cyclobutenediones, cyclic imides and anhydrides via double carbonylation

Methods have been developed for the preparation of reactive iron carbonyl reagents for dicarbonylation of alkynes under various reaction conditions. In most cases, the cyclobutenediones were obtained in moderate to good yields (27-93%). In some cases, the iron carbonyl intermediates were converted to the corresponding benzoquinones (51-80%), cyclicimides (45-65%) and cyclic anhydrides (60-80%) in reasonable yields. The mechanistic pathways and intermediates involved in these processes are discussed.