Synthesis and characterization of [R.sub.2]PN=P[[super i]BuNC[H.sub.2]C[H.sub.2]).sub.3]N: A new bulky electron-rich phosphite for efficient Pd-assisted Suzuki--Miyaura cross-coupling reactions

The synthesis and structural characterization of a new generation of bulky electron-rich phosphines of type [R'.sub.2]PN=P[([i.sub.B]uNC[H.sub.2]C[H.sub.2]).sub.3]N, (R'= Ph, Pr, Bu) where in the pro-azaphosphatrane unit is one of the three bulky electron-rich substituents is reported. The Pd[(OAc).sub.2]/BU catalyst system was particularly efficient for the coupling of arylboronic acids with aryl bromides as well as aryl chlorides to give biaryls in excellent yields.