Synthesis and characterization of new (N-diphenylphosphino)-isopropylanilines and their complexes: crystal structure of (Ph2P=S)NH-C6H4-4-CH(CH3)2 and catalytic activity of palladium(II) complexes in the Heck and Suzuki cross-coupling reactions

Abstract

Three new (N-diphenylphosphino)-isopropylanilines, having isopropyl substituent at the carbon 2- (1) 4- (2) or 2,6- (3) were prepared from the aminolysis of chlorodiphenylphosphine with 2-isopropylaniline,4-isopropylaniline or 2,6-diisopropylaniline, respectively, under anaerobic conditions. Oxidation of 1,2 and 3 with aqueous hydrogen peroxide, elemental sulfur or gray selenium gave the corresponding oxides, sulfides and selenides (Ph2P=E)NH-C6H4-2-CH(CH3)(2), (Ph2P=E)NH-C6H4-4-CH(CH3)(2) and (Ph2P=E)NH-C6H4-2,6-[CH(CH3)(2)](2), where E = O, S, or Se, respectively. The reaction of [M(cod)Cl-2] (M = Pd, Pt; cod = 1,5-cyclooctadiene) with two equivalents of 1,2 or 3 yields the corresponding monodendate complexes [M((Ph2P)NH-C6H4-2-CH(CH3)(2))(2)Cl-2], M = Pd 1d, M = Pt 1e, [M((Ph2P)NH-C6H4-4-CH(CH3)(2))(2)Cl-2], M = Pd 2d, M = Pt 2e and [M((Ph2P)NH-C6H4-2,6-(CH(CH3)(2))(2))(2)Cl-2], M = Pd 3d, M = Pt 3e, respectively. All the compounds were isolated as analytically pure substances and characterized by NMR, IR spectroscopy and elemental analysis. Furthermore, representative solid-state structure of [(Ph2P=S)NH-C6H4-4-CH(CH3)(2)] (2b) was determined using single crystal X-ray diffraction technique. The complexes 1d-3d were tested and found to be highly active catalysts in the Suzuki coupling and Heck reaction, affording biphenyls and stilbenes, respectively. Copyright (C) 2009 John Wiley & Sons, Ltd.