Tailoring Buchwald-Type Phosphines with Pyrimidinium Betaines as Versatile Aryl Group Surrogates

A derivatization of dialkylbiarylphosphines
consisting in the formal replacement of their distal aryl group by
a pyrimidinium betaine is reported. Two achiral representatives of
this new class of Buchwald-type phosphines have been successfully
synthesized through two strategies. The first one is based on a last
stage introduction of the phosphino moiety, and the second one consists
in a modular, one-pot, three-step procedure starting from an o-bromoaryl phosphine. The resulting phosphines have been
coordinated onto gold­(I) and palladium­(II) centers and have been employed
as supporting ligands in Pd-catalyzed Suzuki–Miyaura cross-coupling
of aryl halide substrates.