Pd−P(t-Bu)3-Catalyzed Consecutive Cross-Coupling of p-Phenylenedizinc Compound with Two Different Electrophiles Leading to Unsymmetrically 1,4-Disubstituted Benzenes

Pd-P(t-Bu)3 was found to be a chemoselective catalyst for the reaction of p-phenylenedizinc compound with equimolar amounts of carbon electrophiles to afford the single cross-coupling products in good yields, effectively suppressing the formation of double cross-coupling products. The subsequent additions of other electrophiles to the resulting solutions caused the second cross-coupling of the incipient products to take place, achieving a novel and efficient one-pot synthesis of unsymmetrically 1,4-disubstituted benzenes. The origin of the observed high chemoselectivity was speculated.