Polymer biquinolyl-containing complexes of Pd(ii) as efficient catalysts for cyanation of aryl and vinyl halides with K4Fe(CN)6

Abstract

A catalytic system for cyanation of aryl and vinyl halides with K₄Fe(CN)₆ based on a structurally tunable and nontoxic polymer backbone of polyamic type with biquinolyl fragments in the polymer chain capable of coordination to Pd^II ions is developed. The catalyst is eligible for thermal and microwave activation; in the latter case the reaction time is dramatically decreased. Cyanation of vinyl bromides occurs stereoselectively, and the configuration of the starting alkene is retained; even for Z-isomers the impact of configuration inversion is less than 5%. The polymer-based Pd catalyst is applicable for one-pot multi-step synthesis of the precursors of mesogenic structures of biphenyl type. Consecutive cross-coupling and cyanation reactions can be performed in the presence of the same portion of catalyst, in the same solvent, without isolation of intermediate products.