Mixed-ligand aminoalcohol-dicarboxylate copper(II) coordination polymers as catalysts for the oxidative functionalization of cyclic alkanes and alkenes

Abstract

New copper(II) catalytic systems for the mild oxidative C–H functionalization of cycloalkanes and cycloalkenes were developed, which are based on a series of mixed-ligand aminoalcohol-dicarboxylate coordination polymers, namely [Cu2(μ-dmea)2(μ-nda)(H2O)2]n·2nH2O (1), [Cu2(μ-Hmdea)2(μ-nda)]n·2nH2O (2), and [Cu2(μ-Hbdea)2(μ-nda)]n·2nH2O (3) that bear slightly different dicopper(II) aminoalcoholate cores, as well as on a structurally distinct dicopper(II) [Cu2(H4etda)2(μ-nda)]·nda·4H2O (4) derivative [abbreviations: H2nda, 2,6-naphthalenedicarboxylic acid; Hdmea, N,N′-dimethylethanolamine; H2mdea, N-methyldiethanolamine; H2bdea, N-butyldiethanolamine; H4etda, N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine]. Compounds 1–4 act as homogeneous catalysts in the three types of model catalytic reactions that proceed in aqueous acetonitrile medium under mild conditions (50–60°C): (i) the oxidation of cyclohexane by hydrogen peroxide to cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone, (ii) the oxidation of cycloalkenes (cyclohexene, cyclooctene) by hydrogen peroxide to a mixture of different oxidation products, and (iii) the single-pot hydrocarboxylation of cycloalkanes (cyclopentane, cyclohexane, cycloheptane, cyclooctane) by carbon monoxide, water, and a peroxodisulfate oxidant into the corresponding cycloalkanecarboxylic acids. The catalyst and substrate scope as well as some mechanistic features were investigated; the highest catalytic activity of 1–4 was observed in the hydrocarboxylation of cycloalkanes, allowing to achieve up to 50% total product yields (based on substrate).

Synergistic Copper/Enamine Catalysis for the Regio-, Stereo-, and Enantioselective Intermolecular α-Addition of Aldehydes to Allenamides

“…6f However, when 20 mol% of p-methylbenzoic acid A1 was added, the yield and enantioselectivity were only slightly improved (28% and 16:84 respectively, entry 4). Then, we thought that the addition of external nitrogen ligand would prevent the potential formation of (prolinol) copper (I) complex, 12 which could sequestrate the organocatalyst in such non-polar, weakly coordinating solvent as toluene. Indeed, with a combination of 20 mol% of A1 and 2,2'-bipyridine L1, the yield and enantioselectivity were further improved to 46% and 88:12 er, respectively (entry 5).…”

“…Although L-proline gave essentially racemic mixture (entry 6), prolinol based organocatalysts (C3, C5) gave the best enantioselectivities, with C5 giving an excellent enantiomeric ratio of 95.5:4.5, albeit affording 3aa in a somewhat lower yield (entry 9). Both McMillan-type catalysts (C6-C7) and cinchona alkaloids-derived amine catalyst C8 gave lower enantioselectivity (entry [10][11][12].…”

Homogeneous oxidation of alcohol and alkene with copper (II) complex in water

“…Copper(II) catalytic systems with mixed-ligand aminoalcohol-dicarboxylate coordination polymers act as homogeneous catalysts in aqueous acetonitrile under mild conditions (50-60 • C): the oxidation of cyclohexene through H 2 O 2 and in the presence of a trifluoroacetic acid promoter results in total product yields (∼15-18% based on the substrate). [32][33][34][35][36] Cu-MOF, [Cu(bpy)(H 2 O) 2 (BF 4 ) 2 (bpy)] (bpy: 4,4'-bipyridine), exhibited catalytic activity and high selectivity in the allylic oxidation of cyclohexene with molecular oxygen under solvent-free conditions (TON = 13-37). 25 However, these catalysts show lower selectivity than our systems.…”

“…44,45 The obtained products and yields are also comparable with or even superior to those achieved using other related copper catalysts bearing carboxylate and Nbased ligands. [32][33][34][35][36]…”

Synthesis, Structural Characterization, Photophysical Properties, and Antibacterial Assessment of Silver(I)-Thione Coordination Polymers Based on a Competition between Nitrate Anion and Coanions CF3SO3–, ClO4–, BF4–, PF6–, and SbF6–

“…Thus, it is pertinent to understand and control the subtle factors that have some impact on the formation of these materials. The self-assembly progress is highly influenced by several factors such as the ligand and metal nature, − the counterions, − the experimental conditions, − the solvents, − and the metal to ligand ratio. , It is noteworthy to mention that, in metal–organic crystal engineering, predicting the coordination polymer topology when mixed anions are used is more difficult because several factors are controlling the framework formation of coordination polymers including the size, geometry, coordinating ability, and selectivity of anions to participate in the structure. − On the other hand, the role of the anions in the macromolecule chemistry is of a great interest because of its application in ion-pair recognition and especially in anion exchange. − Although a good number of metal mixed-ligand complexes were reported, − to the best of our knowledge there is no report in the literature about the synthesis of metal mixed-anion complexes. Mixed anion complexes are attractive due to their potential applications and their new structures.…”