Supported and Non-Supported Ruthenium(II)/Phosphine/[3-(2-Aminoethyl)aminopropyl]trimethoxysilane Complexes and Their Activities in the Chemoselective Hydrogenation of trans-4-Phenyl-3-butene-2-al

Abstract

Syntheses of four new ruthenium(II) complexes of the [RuCl2(P)2(N)2] type using 2-(diphenylphosphino)ethyl methyl ether (P~O) as ether-phosphine and triphenylphosphine (PPh3) as monodentate phosphine ligands in the presence of [3-(2-aminoethyl)aminopropyl]trimethoxysilane as diamine co-ligand are presented for the first time. The reactions were conducted at room temperature and under an inert atmosphere. Due to the presence of the trimethoxysilane group in the backbone of complexes 1 and 2 they were subjected to an immobilization process using the sol-gel technique in the presence of tetraethoxysilane as cross-linker. The structural behavior of the phosphine ligands in the desired complexes during synthesis were monitored by 31P{1H}-NMR. Desired complexes were deduced from elemental analyses, Infrared, FAB-MS and 1H-, 13C- and 31P-NMR spectroscopy, xerogels X1 and X2 were subjected to solid state, 13C-, 29Si- and 31P-NMR spectroscopy, Infrared and EXAF. These complexes served as hydrogenation catalysts in homogenous and heterogeneous phases, and chemoselective hydrogenation of the carbonyl function group in trans-4-phenyl-3-butene-2-al was successfully carried out under mild basic conditions.

Diphenyl(2-propoxyethyl)phosphine

“…Due to this feature, the (ether) oxygen atom can easily be displaced by an incoming substrate. In addition, the oxygen function, which may be regarded as an intramolecular solvent, is able to stabilize a transition-metal fragment after substrate dissociation, and therefore, decomposition is suppressed [4][5][6][7][8][9]. Thus, ether phosphines are capable of making available and protecting vacant coordination sites and lead to an improvement in both catalytic and stoichiometric reactions [5][6][7][8][9] The strength of the metal oxygen bond in (ether phosphine)ruthenium complexes depends on the O nucleophilicity of the ether moiety, the ring size of the cyclic ether, the number and position of the oxygen atoms in the ring, and the basicity at the metal.…”

Design, Synthesis, Characterization of Novel Ruthenium(II) Catalysts: Highly Efficient and Selective Hydrogenation of Cinnamaldehyde to (E)-3-Phenylprop-2-en-1-ol

“…In 1995, Noyori discovered that complexes derived from the parent [RuCl 2 (diphosphine) 2 (diamine) 2 ] can be utilized as homogeneous catalysts for the hydrogenation of α,β-unsaturated ketones [2,3,4]. In particular, these systems were found to be more effective in the chemoselective hydrogenation of carbonyl functional groups in the presence of olefins [10,11,12,13,14,15,16,17,18,19,20,21,22]. In this aspect, hydrogenations of C=C and C=O functionalities have found important applications in organic and fine chemicals synthesis [14,15,16,17,18,19,20,21,22,23,24,25,26].…”

Diaminosilane-functionalized on silicate-stabilised hydrotalcite (MA-HTSi-DA): As potential catalyst for nitro-aldol condensation

“…Table 3. It is known from the previously published reports that the nitro-aldol condensation can follow 21 two types of mechanism, that is, the imine or ion-pair mechanism to yield dehydrated and 22 alcohol products, respectively [50][51][52][53]. The possible mechanism of the nitro-aldol condensation 23 is proposed and shown in Scheme 3.…”