Pd-PEPPSI-IPent: Low-Temperature Negishi Cross-Coupling for the Preparation of Highly Functionalized, Tetra-ortho-Substituted Biaryls

摘要

Biaryls are important motifs seen in the structures of many biologically active compounds and organic materials. Thus, the development of efficient bond-forming procedures between sp~2-hybridized carbon atoms has been pursued intensively by both academic and industrial scientists. The synthesis of biaryl compounds began with the century-old Ullmann reaction and has evolved into a wide variety of Ni-and Pd-catalyzed cross-coupling procedures. Organotin (Stille-Migita) and organoboron (Suzuki-Miyaura) reagents have been used most widely as the transmetalating partner in cross-coupling reactions; organozincs (Negishi coupling) are the most reactive partners, but have been employed to a lesser extent owing primarily to their increased basicity and moisture sensitivity.