Palladium-catalyzed cross-alkynylation of aryl bromides by sodium tetraalkynylaluminates.
Sodium tetraalkynylaluminates (1-4), prepared from NaAlH4 and terminal alkynes, cross-couple with aryl bromides in the presence of Pd(0) and Pd(II) catalysts. The reactions take place in boiling THF or DME. The process is applicable to both homo- and heterocyclic aryl bromides and can be used for conversion of polybromo compounds into polyalkynes. The reactions are high yielding and selective, free of undesired homocoupling and hydrogenolysis processes. The reagents selectively react with the ring-bound bromine atoms but do not affect chloro, cyano, triflate, or ester functions.
Gelman
Dmitri
D
Department of Organic Chemistry, The Hebrew University, Jerusalem 91904, Israel.
Tsvelikhovsky
Dmitry
D
Molander
Gary A
GA
Blum
Jochanan
J