Efficient Suzuki Coupling of Aryl Chlorides Catalyzed by Palladium(0) with a P,N Heteroligand and Isolation of Unsaturated Intermediates

A mixture of Pd₂(dba)₃/[η-C₅H₄CHN(C₆H₅)]Fe[η-C₅H₄P(t-Bu)₂] (1) efficiently catalyzes the Suzuki cross-couplings of a range of arylboronic acids and aryl chlorides, affording the desired biaryl products in high isolated yields. Two catalytically active Pd(0) intermediates, viz. 16-electron [η-C₅H₄CHN(C₆H₅)]Fe[η-C₅H₄P(t-Bu)₂]Pd(dba) (2) and 14-electron linear Pd{[η-C₅H₄CHN(C₆H₅)]Fe[η-C₅H₄P(t-Bu)₂]}₂ (3) together with an oxidative addition product are isolated and crystallographically established.