Palladiumdichloride (ferrocenylethynyl)phosphanes and their use in Pd-catalyzed Heck–Mizoroki- and Suzuki–Miyaura carbon–carbon cross-coupling reactions

Abstract

In this work the synthesis of phosphane selenides (FcC C) n Ph 3− n P Se ( 2a, n = 1; 2b, n = 2; 2c, n = 3; Fc = ferrocenyl, (η 5-C 5H 4)(η 5-C 5H 5)Fe) from (FcC C) n Ph 3− n P ( 1a, n = 1; 1b, n = 2; 1c, n = 3) and selenium is described to estimate the σ-donor properties of these systems by 31P{ 1H} NMR spectroscopy. Progressive replacement of phenyl by ferrocenylethynyl causes a shielding of the phosphorus atom with increasing of the 1 J( 31P– 77Se) coupling constants. The palladiumdichloride metal-organic complexes [((FcC C) n Ph 3− n P) 2PdCl 2] ( 3a, n = 1; 3b, n = 2; 3c, n = 3) have been used as (pre)catalysts in the Suzuki–Miyaura (reaction of 2-bromo-toluene ( 4a) and 4-bromo-acetophenone ( 4b), respectively, with phenyl boronic acid ( 5) to give 2-methyl biphenyl ( 6a) and 4-acetyl biphenyl ( 6b)) and in the Heck–Mizoroki reaction (treatment of iodobenzene ( 7) with tert-butyl acrylate ( 8) to give E- tert-butyl cinnamate ( 9)). The structures of molecules 1a, 1c, 2c, and 3c in the solid state were determined by single X-ray structure analysis showing that the structural parameters of these systems are unexceptional and correspond to those of related phosphanes, seleno phosphanes, and palladium dichloride complexes.