Palladium-catalysed amination reactions using cobalt-containing bulky phosphane ligands

Animations of aryl bromides by morpholine have been investigated using palladium complexes as catalyst precursors modified by the cobalt-containing phosphane ligand [(mu-PPh2CH2PPh2)CO2(CO)(4)][mu,eta-PhC equivalent to CP(tBu)(2)] (1). Reactions were carried out under various conditions with satisfactory results. The components of the optimised reaction conditions consist of 1.0 mmol of aryl bromide, 1.2 equiv. of morpholine, 1.4 equiv. of NaOtBu, 1 mL of toluene and 1 mol-% of a 1:1 mixture of 1 and Pd(OAc)(2), In contrast, related animations using [(mu-PPh2CH2PPh2)CO2(CO)(4)][mu,eta-pyC equivalent to CP(tBu)(2)] (2), [(mu-PPh2CH2PPh2)CO2(CO)(4)][{mu,eta-pyC equivalent to CP(cy)(2)}] (3) and [(t-PPh2CH2PPh2)CO2(CO)(4)][mu,eta-PhC equivalent to CP(iPr)(2)] (4) as phosphane ligands do not exhibit comparable efficiency. A novel palladium complex 5, i.e. Pd(OAc) chelated by deprotonated I was obtained from the reaction of I with Pd(OAc)(2). As revealed by the crystal structure, an orthometallation process occurs between the phenyl ring of 1 and the palladium ion. Presumably, the process is accompanied by release of one equivalent of acetic acid. The coordinated acetate ligand binds to the palladium ion in a bidentate chelating mode. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).