On-Water Synthesis of 2‑Substituted Quinolines from 2‑Aminochalcones Using Benzylamine as the Nucleophilic Catalyst

On-water synthesis of 2-substituted quinolines from 2-aminochalcone derivatives was developed using benzylamine as the nucleophilic catalyst. Various 2-aminochalcones could be applied to this protocol, and the desired 2-substituted quinoline products were isolated in excellent yields by simple filtration. Furthermore, we elucidated the role of benzylamine in this transformation and provided the detailed reaction mechanism. This protocol has several additional advantages, such as simple operation, broad substrate scope, good functional group tolerance, easy product isolation, recycling of the catalyst, and gram-scale synthesis

Discrete Mercury(II) Complexes, One-Dimensional and Palladium(II)-Mediated Two-Dimensional Silver(I) Coordination Polymers of NS₂-Macrocycle: Synthesis and Structural Characterization

A range of thiaphilic mononuclear (Hg2+ and Ag+) and heterobinuclear (Ag+/Pd2+) complexes (1−6) of an NS2-donor macrocycle L with discrete and networked forms were prepared and structurally characterized. Reaction of L with HgCl2 afforded a unique 1:1 (cationic/anionic) complex [Hg2(L)Cl5][Hg(L)Cl] (1). Reaction of L with Hg(ClO4)2 yielded the sandwich-type 1:2 (metal-to-ligand) complex [Hg(L)2](ClO4)2 (2). Contrasting with the mercury(II) salts, the reactions of L with AgX (X = NO3− and CF3SO3−) yielded an isostructural one-dimensional (1D) zigzag networks [Ag(L)X]n (3; X = NO3− and 4; X = CF3SO3−) in which each ring of L is exo-coordinated via two S atoms and one N atom to a silver ion which is also bound to one S atom in the neighboring L such that the overall coordination geometry about each silver is four-coordinate. Whereas, reaction of L with K2PdCl4 gave a discrete exocyclic complex 5, [cis-Cl2Pd(L)]. Through a successive reaction of the complex 5 with AgNO3, a heterobinuclear two-dimensional (2D) coordination polymer 6, [Pd(L)Ag2.5(NO3)4.5(H2O)0.5]n, utilizing exocyclic Pd(II) and Ag(I) was isolated and characterized

Discrete Mercury(II) Complexes, One-Dimensional and Palladium(II)-Mediated Two-Dimensional Silver(I) Coordination Polymers of NS₂-Macrocycle: Synthesis and Structural Characterization

A range of thiaphilic mononuclear (Hg2+ and Ag+) and heterobinuclear (Ag+/Pd2+) complexes (1−6) of an NS2-donor macrocycle L with discrete and networked forms were prepared and structurally characterized. Reaction of L with HgCl2 afforded a unique 1:1 (cationic/anionic) complex [Hg2(L)Cl5][Hg(L)Cl] (1). Reaction of L with Hg(ClO4)2 yielded the sandwich-type 1:2 (metal-to-ligand) complex [Hg(L)2](ClO4)2 (2). Contrasting with the mercury(II) salts, the reactions of L with AgX (X = NO3− and CF3SO3−) yielded an isostructural one-dimensional (1D) zigzag networks [Ag(L)X]n (3; X = NO3− and 4; X = CF3SO3−) in which each ring of L is exo-coordinated via two S atoms and one N atom to a silver ion which is also bound to one S atom in the neighboring L such that the overall coordination geometry about each silver is four-coordinate. Whereas, reaction of L with K2PdCl4 gave a discrete exocyclic complex 5, [cis-Cl2Pd(L)]. Through a successive reaction of the complex 5 with AgNO3, a heterobinuclear two-dimensional (2D) coordination polymer 6, [Pd(L)Ag2.5(NO3)4.5(H2O)0.5]n, utilizing exocyclic Pd(II) and Ag(I) was isolated and characterized

Copper(I), Silver(I), and Palladium(II) Complexes of a Thiaoxamacrocycle Displaying Unusual Topologies

Coordination behavior of the 14-membered dibenzo-O2S2 macrocycle, L, with the soft metal ions such as Pd(II), Cu(I), and Ag(I) is reported. The X-ray structures of the complexes have been determined, and a range of less common structural types, including mono-, di-, and multinuclear species with discrete and continuous forms were obtained. A two-step approach via reaction of dichloro-palladium(II) complex of L as a metalloligand, with L through a treatment of silver(I) perchlorate, led to the formation of bis(ligand) monopalladium(II) complex, [Pd(L)2]·2ClO4·2CH3NO2 (1). In this case, the square-planar stereochemical demand of Pd(II) coupled with the coordination of the S2-donors of L to a metal center results in the formation of the bis(ligand)-type mononuclear complex. In 1, the ether oxygens of the ring are unbound. L reacts with CuBr to yield related 2:2:2 (metal/ligand/anion) complex of type [Cu2Br2(L)2] (2), in which two ligand molecules are linked by a rhomboid-type Cu−Br2−Cu cluster unit. However, the parallel reaction with CuI afforded the mixture of the isostructural 2:2:2 type complex [Cu2I2(L)2] (3a) and double-stranded 1D coordination polymer {[Cu2I2(L)2]·2CH3CN}n (3b). The framework of 3b contains four bridging L coordinated to a rhomboidal Cu−I2−Cu motif through the exomonodentate Cu−S bonds. Again, the ether oxygens do not coordinate in copper(I) halide complexes. The observed different reactivity between copper(I) bromide and copper(I) iodide was also confirm by an XRPD measurement. Unlike the Pd(II) and Cu(I) cases, L afforded an unusual tris(L)-disilver(I) (club-sandwich-type) complex [Ag2(L)3](PF6)2 (4) on its reaction with AgPF6. Each silver adopts a trigonal planar coordination environment with coordination sites occupied by two S atoms from one terminal ligand, and by one S atom from the bridging ligand; once again the ether oxygens are not coordinated. An NMR titration of the formation of complex 4 confirmed that the Ag/L stoichiometry of 2:3 found in the solid state is also maintained in solution

Synthesis of 2‑Substituted Quinolines from 2‑Aminostyryl Ketones Using Iodide as a Catalyst

A new protocol for the synthesis of 2-substituted quinolines from 2-aminostyryl ketones has been developed using iodide as a nucleophilic catalyst. Conjugate addition of iodide to 2-aminostyryl ketones yielded the corresponding β-iodoketones, which could have a conformation where the amino and carbonyl groups are proximal through free rotation about the C_α–C_β single bond. Subsequent condensation between the amino and carbonyl groups followed by elimination of hydrogen iodide provided the corresponding quinolines, with regeneration of the iodide catalyst

Sulfur-Containing Mixed-Donor Tribenzo-Macrocycles and Their Endo- and Exocyclic Supramolecular Silver(I) and Copper(I) Complexes

New sulfur-containing mixed-donor macrocycles L1−L4 with different donor sets and/or ring sizes (L1, 20-membered O3S2; L2, 20-membered NO2S2; L3, 20-membered O2S3; and L4, 23-membered O4S2) were synthesized and structurally characterized by X-ray analysis. A comparative investigation of the coordination behavior of these macrocyclic ligands with silver(I) salts and copper(I) iodide is reported. The X-ray structures of seven complexes (1−7) have been determined, and a range of structural types and coordination modes, including mono- to multinuclear and endo- to exocyclic ones via M−S bonds, is shown to occur. In all seven complexes, the ether oxygens of each ring are unbound. Reactions of L1−L4 with the silver(I) salts (ClO4−, BF4−, and NO3−) afforded four complexes with different topologies: the exocyclic 1-D coordination polymer [Ag(L1)(ClO4)]n (1), the endocyclic 1:1 monomer complex [Ag(L2)]ClO4·CH3OH (2), the endo-/exocyclic 1-D coordination polymer {[Ag2(L2)(CH3OH)](BF4)2}n (3), and the cyclic dimer complex [Ag2(L3)2(NO3)2]·2CH3CN (4). NMR titrations of L1 and L2 with silver(I) perchlorate were carried out to explore their complexation behavior in solution and also for comparison with the solid state structures. As well, reaction of the above ligands with copper(I) iodide afforded the exocyclic dimer, [Cu2I2(L1)2]·CH2Cl2 (5), linked with diamond-type Cu−I2−Cu unit, the exocyclic monomer complex [CuI(L3)]·CH2Cl2 (6), and the emissive 1-D poly(cyclic dimer) complex {[Cu4I4(L4)2]·CH2Cl2}n (7) linked by a cubane-type Cu4I4 unit. The formation of both the discrete and continuous supramolecular complexes with copper(I) iodide is discussed in terms of a ligand-directed “sulfur-to-sulfur” distance effect

Sulfur-Containing Mixed-Donor Tribenzo-Macrocycles and Their Endo- and Exocyclic Supramolecular Silver(I) and Copper(I) Complexes

New sulfur-containing mixed-donor macrocycles L1−L4 with different donor sets and/or ring sizes (L1, 20-membered O3S2; L2, 20-membered NO2S2; L3, 20-membered O2S3; and L4, 23-membered O4S2) were synthesized and structurally characterized by X-ray analysis. A comparative investigation of the coordination behavior of these macrocyclic ligands with silver(I) salts and copper(I) iodide is reported. The X-ray structures of seven complexes (1−7) have been determined, and a range of structural types and coordination modes, including mono- to multinuclear and endo- to exocyclic ones via M−S bonds, is shown to occur. In all seven complexes, the ether oxygens of each ring are unbound. Reactions of L1−L4 with the silver(I) salts (ClO4−, BF4−, and NO3−) afforded four complexes with different topologies: the exocyclic 1-D coordination polymer [Ag(L1)(ClO4)]n (1), the endocyclic 1:1 monomer complex [Ag(L2)]ClO4·CH3OH (2), the endo-/exocyclic 1-D coordination polymer {[Ag2(L2)(CH3OH)](BF4)2}n (3), and the cyclic dimer complex [Ag2(L3)2(NO3)2]·2CH3CN (4). NMR titrations of L1 and L2 with silver(I) perchlorate were carried out to explore their complexation behavior in solution and also for comparison with the solid state structures. As well, reaction of the above ligands with copper(I) iodide afforded the exocyclic dimer, [Cu2I2(L1)2]·CH2Cl2 (5), linked with diamond-type Cu−I2−Cu unit, the exocyclic monomer complex [CuI(L3)]·CH2Cl2 (6), and the emissive 1-D poly(cyclic dimer) complex {[Cu4I4(L4)2]·CH2Cl2}n (7) linked by a cubane-type Cu4I4 unit. The formation of both the discrete and continuous supramolecular complexes with copper(I) iodide is discussed in terms of a ligand-directed “sulfur-to-sulfur” distance effect

Enantioselective Synthesis of Tetrahydroquinolines from 2‑Aminochalcones via a Consecutive One-Pot Reaction Catalyzed by Chiral Phosphoric Acid

A new asymmetric protocol for the synthesis of chiral tetrahydroquinolines from 2-aminochalcones via a two-step one-pot consecutive process (cyclization/asymmetric reduction) has been developed using chiral phosphoric acid as the sole catalyst. 2-Aminochalcones were converted into the corresponding quinolines through chiral phosphoric acid-catalyzed dehydrative cyclization, and the resultant quinolines were subsequently reduced to the chiral tetrahydroquinolines via chiral phosphoric acid-catalyzed asymmetric reduction with Hantzsch ester. Various 2-aminochalcones could be applicable to this protocol, and the desired tetrahydroquinolines were obtained in excellent yields and with excellent enantioselectivities. Furthermore, the utility of this protocol has been successfully demonstrated in the highly efficient synthesis of estrogen receptor modulator

Unsymmetrical Calixcrowns Incorporating Hard and Soft Loops as a New Scaffold for Multinuclear Endo/Exocyclic Complexation and Networking

Unsymmerical calix[4]crowns containing [(O4S)(O5)] (L1) and [(O4S2)(O5)] (L2) as crown loops were employed as new scaffolds both for complexation studies and for network formation. Reactions of L1 and L2 with KI in the presence of CuI afforded a copper(I) iodide cluster linked 1D-type endocyclic dipotassium(I) complex [K2(L1)(Cu7I9)]n (1) and a copper(I) iodide cluster linked 1D-type endocyclic monopotassium(I) complex [KL2(μ2-Cu3I4)]n (2), respectively. By comparison, the reaction of L2 with KPF6 in the presence of CuI and HgI2 afforded the 1-D endocyclic potassium(I) complex [K(L2)(CuHgI4)]n (3), linked with a CuHgI4 cluster unit. The formation of homo- and heterodinuclear complexes in solution was also confirmed by comparative NMR studies

Solvent-Dependent Networking of O₂S₂-Macrocycle with Silver Perchlorate into One- and Two-Dimensional Coordination Polymers

The solvent-dependent double-stranded one-dimensional (1-D) coordination polymer [Ag2L2(ClO4)2]n (1) and another 1-D polymer {[Ag2L2(CH3CN)]·2ClO4}n (2a) with the shape of a cut of tube along the long axis were obtained in the reactions of a 16-membered O2S2-macrocycle L with silver(I) perchlorate in DCM/MeOH and CH3CN, respectively. Time-dependent crystallization experiments unambiguously show that 2a is a kinetic product and transforms into a thermodynamically more stable [AgLClO4]n (2b) with a two-dimensional square-grid structure