Direct synthesis of terminal alkynes via pd-catalyzed cross coupling of aryl and lkenyl halides with ethynylmetals containing zn, mg, and sn. Critical comparison of countercations

摘要

Several Pd-catalyzed cross-coupling procedures for the synthesis of alkynes were reported in the mid 1970s. Of these, the Sonogashira protocol involving the treat- Ment of terminal alkynes with organic halides and an Amine base, e.g., Et_2NH, in the presence of catalytic Quantities of a Pd-phosphin complex and CuI has been Mst widely used presumably due to generally favorable Results and operational simplicity associated with it.