Copper-Catalyzed Reductive Ireland-Claisen Rearrangements of Propargylic Acrylates and Allylic Allenoates.

The copper-catalyzed reductive Ireland-Claisen rearrangement of propargylic acrylates led to 3,4-allenoic acids. The use of silanes or pinacolborane as stoichiometric reducing agents and triethylphosphite as a ligand facilitated the divergent and complementary selectivity for the synthesis of diastereomeric - and -rearranged products, respectively. Copper-catalyzed reductive Ireland-Claisen rearrangement of allylic 2,3-allenoates proceeded effectively only when pinacolborane was used as a reductant to generate various 1,5-dienes in excellent yields and with good diastereoselectivities in some cases.

Helicate-to-tetrahedron transformation of chiral lanthanide supramolecular complexes induced by ionic radii effect and linker length.

Controlled formation of desired lanthanide supramolecular complexes is challenging because of the difficulties in predicting coordination geometry, as well as a labile coordination number. Herein, we explore the effect of ionic radii and linker length on supramolecular species formation. A helicate-to-tetrahedron transformation occurred between [LnL1] and [LnL1] (Ln = La, Sm, Eu, Gd, Tb and Lu).

Design of Functional Chiral Cyclen-Based Radiometal Chelators for Theranostics.

A series of water-soluble chiral cyclen-based chelators with chemical handles for selective targeting have been synthesized (cyclen = 1,4,7,10-Tetraazacyclododecane). Optical studies, relaxivity measurements, and competitive titrations were performed to show the versatility of these chiral chelators. The complexations of L3, L4, and L5 with Lu, Y, Sc and Cu were successfully demonstrated in around 90% to 100% yields.

Unusual Magnetic Field Responsive Circularly Polarized Luminescence Probes with Highly Emissive Chiral Europium(III) Complexes.

Chirality is ubiquitous within biological systems where many of the roles and functions are still undetermined. Given this, there is a clear need to design and develop sensitive chiral optical probes that can function within a biological setting. Here we report the design and synthesis of magnetically responsive Circularly Polarized Luminescence (CPL) complexes displaying exceptional photophysical properties (quantum yield up to 31 % and |g | up to 0.

Copper-catalyzed (4+1) and (3+2) cyclizations of iodonium ylides with alkynes.

The copper(ii)-catalyzed (4+1) cyclizations and copper(i)-catalyzed (3+2) cycloadditions of iodonium ylides and alkynes were successfully developed by employing efficient and safe iodonium ylides instead of traditional diazo compounds. Highly functionalized dimethyl (E)-3-benzylideneindoline-2,2-dicarboxylates and methyl 5-(2-hydroxyphenyl)-2-methoxy-4-phenylfuran-3-carboxylates were conveniently prepared in moderate to excellent yields. The possible reaction mechanisms were also discussed.

Catalytic asymmetric oxo-Diels-Alder reactions with chiral atropisomeric biphenyl diols.

New chiral atropisomeric biphenyl diols , and containing additional peripheral chiral centers with different steric bulkiness and/or electronic properties were synthesized. The X-ray crystal structure of shows the formation of a supramolecular structure whereas that of , containing additional CF substituents, shows the formation of a monomeric structure. Diols - were found to be active organocatalysts in oxo-Diels-Alder reactions in which recorded a 72% ee with trimethylacetaldehyde as a substrate.

Triboluminescence of Centrosymmetric Lanthanide β-Diketonate Complexes with Aggregation-Induced Emission.

Triboluminescence (TL) is a form of light emission induced upon mechanical forces on the material. However, our understanding of this phenomenon is still unclear and more examples are therefore needed in order to elucidate its mechanism. In this work, two types of TL complexes, [Eu(-dbm-Cl₂)₃phen] and [Eu(-dbm-Cl₂)₃phen], which also displays aggregation-induced emission (AIE) were synthesized and investigated for its photo-physical and crystal structural properties.

Synthesis of a Conformationally Stable Atropisomeric Pair of Biphenyl Scaffold Containing Additional Stereogenic Centers.

The synthesis of a new CF₃-containing stereogenic atropisomeric pair of ortho-disubstituted biphenyl scaffold is presented. The atropisomers are surprisingly conformationally stable for isolation. X-ray structures show that their stability comes from an intramolecular hydrogen bond formation from their two hydroxyl groups and renders the spatial arrangement of their peripheral CF₃ and CH₃ groups very different.

Assembly of Lanthanide(III) Cubanes and Dimers with Single-Molecule Magnetism and Photoluminescence.

Discrete lanthanide(III) tetranuclear cubane-like clusters seldom occur throughout the Ln series and behave as single-molecule magnets (SMMs). Herein, a series of cubanes, [Ln(μ-OH)(μ-tfa)(hfa)(phen)] (1-9, Ln = La-Dy (except Pm), tfa = trifluoroacetate, hfa = hexafluoroacetylacetonate, phen = 1,10-phenanthroline), and dinuclear clusters, [Ln(μ-OH)(hfa)(phen)] (10-16, Ln = Tb-Lu), were synthesized and characterized. Two types of clusters were formed due to the change of preferred coordination geometry for lighter and heavier Ln ions which favor nine-coordinated cubanes and eight-coordinated dimers, respectively.

Chiral DOTA chelators as an improved platform for biomedical imaging and therapy applications.

Despite established clinical utilisation, there is an increasing need for safer, more inert gadolinium-based contrast agents, and for chelators that react rapidly with radiometals. Here we report the syntheses of a series of chiral DOTA chelators and their corresponding metal complexes and reveal properties that transcend the parent DOTA compound. We incorporated symmetrical chiral substituents around the tetraaza ring, imparting enhanced rigidity to the DOTA cavity, enabling control over the range of stereoisomers of the lanthanide complexes.

Cascade Amination and Acetone Monoarylation with Aryl Iodides by Palladium/Norbornene Cooperative Catalysis.

A palladium/norbornene cocatalyzed three-component reaction of aryl iodides, O-benzoylhydroxylamines, and acetone is reported. o'-Aminoaryl acetones or o,o'-diaminoaryl acetones are efficiently prepared via tandem ortho-C-H amination/ipso-C-I α-arylation sequence, and the regiospecificity has been confirmed by X-ray analysis. The proposed method addresses the condensation/amination of free-N-H-bearing substrates in acetone monoarylations and the synthesis of extremely congested 2,6-disubstituted aryl acetones.

Regioselective Synthesis of Polycyclic and Heptagon-embedded Aromatic Compounds through a Versatile π-Extension of Aryl Halides.

A versatile π-extension reaction was developed based on the three-component cross-coupling of aryl halides, 2-haloarylcarboxylic acids, and norbornadiene. The transformation is driven by the direction and subsequent decarboxylation of the carboxyl group, while norbornadiene serves as an ortho-C-H activator and ethylene synthon via a retro-Diels-Alder reaction. Comprehensive DFT calculations were performed to account for the catalytic intermediates.

Mechanistic Investigation of Inducing Triboluminescence in Lanthanide(III) β-Diketonate Complexes.

In this work, we synthesized a series of lanthanide(III) β-diketonate complexes to investigate the induction of triboluminescence. Triboluminescence (TL) spectra, solid-state emission spectra, and luminescence lifetimes of the complexes were obtained to prove consistent emitting species for steady-state and triboluminescence measurements. Detailed analyses of the crystal lattice packing were conducted in an attempt to correlate crystal symmetry, gas discharge, and structural arrangements with "triboexcitation", and it is found that either noncentrosymmetric or centrosymmetic compounds can be TL-active.

Lanthanide supramolecular helical diastereoselective breaking induced by point chirality: mixture or P-helix, M-helix.

The self-assembly of lanthanide (europium or lanthanium) bimetallic triple helicates from two closely related chiral ligands resulted in a very different supramolecular phenomenon. One gave rise to significantly diastereoselective formation of a triple helicate, whereas the other led to diastereoselective breaking to generate a mixture of P and M diastereomers in ∼1 : 1.1 ratio.

Synthesis and characterisation of first row transition metal complexes of functionalized 1,2,4-benzothiadiazines.

Reaction of the novel ligand 3-(2'-pyridyl)-benzo-1,2,4-thiadiazine (L) with the transition metal chloride salts MCl2·xH2O (M(II) = Mn, Fe, Co, Cu and Zn) in a 2 : 1 mole ratio afforded the mononuclear octahedral (high spin) complexes L2MCl2 (1a-1e respectively) in which L binds in a chelate fashion via N(2) and the pyridyl N atoms. In the case of CuCl2 the intermediate 1 : 1 four-coordinate complex LCuCl2 (2) was also isolated which adopts a polymeric structure with pseudo-square planar molecules linked via long Cu···S contacts (d(Cu···S) = 2.938(1) Å) in the apical position.

N,N'-(Ethane-1,2-di-yl)bis-(methane-sulfon-amide).

The mol-ecular structure of the title compound, C4H12N2O4S2, has crystallographic inversion symmetry. The central N-C-C-N moiety was refined as disordered over two sets of sites with an approximate occupancy ratio of 3:1 [0.742 (15):0.

Synergic anion and cation coordination using the tripodal aluminate anion [MeAl(2-py)(3)](-) (py = 2-pyridyl).

The coordination of AlCl(3) by the complex [{MeAl(2-py)(3)}Li.thf] () gives the unusual product [{MeAl(2-py)(3)}(2)Al](+)[{MeAl(2-py)(3)}Li](2)(mu-Cl)(-) (), in which the [MeAl(2-py)(3)](-) aluminate anion of acts cooperatively in the coordination of an Al(3+) cation and Cl(-) anion.

Metal and ligand substitution of the aluminium tris-pyridyl ligands [RAl(2-py')(3)](-) (R = Et, (n)Bu, (s)Bu, (t)Bu; 2-py' = 2-pyridyl, 3-methyl-2-pyridyl, 5-methyl-2-pyridyl, 6-methyl-2-pyridyl).

A series of tris-pyridyl complexes [RAl(2-py)(3)]Li.thf [2-py = 2-pyridyl; R = Et (1); (n)Bu (2); (s)Bu (3), (t)Bu (4)] were prepared by the sequential reaction of AlCl(3) with RLi then 2-Li-py in thf. The related complexes [MeAl{2-(3-Me)py}(3)]Li(mu-Br)Li(thf)(3) (5), [MeAl{2-(5-Me)py}(3)]Li.

Synthesis and structure of the Li13 cage [[[O-P(mu-NtBu)]2Li2]3(LiCl)6Li(Cl/OnBu)0.5(thf)7], containing a [O-P(mu-NtBu)]2(2-) dianion.

The hydrolysis of [ClP(mu-NtBu)]2 with H2O-Et3N in thf, followed by in situ lithiation with nBuLi gives the Li13 cage [[[O-P(mu-NtBu)]2Li2]3(LiCl)6Li(Cl/OnBu)0.5(thf)7], containing a [O-P(mu-NtBu)]2(2-) dianion that is isoelectronic with ligands of the type [(RN)P(mu-NR)]2(2-).