Orthopalladated triaryl phosphite complexes as highly active catalysts in biaryl coupling reactions

Orthopalladation of inexpensive, commercially available tris(2,4-di-tert-butylphenyl) phosphite gives a dimeric complex 3 which proves to be an extremely active catalyst in biaryl coupling reactions, giving unprecedented turnover numbers of up to 1 000 000 [mol product (mol Pd)(-1)] and turnover frequencies of nearly 900 000 [mol product (mol Pd)(-1) h(-1)] in the Suzuki reaction and turnover numbers of up to 830 000 in the Stille reaction.