Metal complexes of chiral pyridine ligands. X-ray structure of nitratobis {2-(2S)-2-pyrrolidinyl]pyridine} copper (II) nitrate

Cobalt(II), nickel(II), and copper(II) complexes of 2-[(2S)-2-pyrrolidinyllpyridine (L) have been synthesized and characterized. The crystal structure of the complex [Cu(L)₂(NO₃)]NO₃ has been determined by X-ray diffraction. Crystals are monoclinic, space groupP2+, witha=10.766(3).b=7.525(2),c=13.447(4) Å. =104.64(2)°. and Z=2. The structure consists of [Cu(L)₂(NO₃)]⁺ cations and NO ₃ ^t- anions. The copper atom has a distorted trigonal bipyramidal coordination geometry with the two pyrrolidine nitrogens and one nitrate oxygen occupying the equatorial positions and the two pyridine nitrogens at the apices. The crystalline cohesion is ensured by a network of hydrogen bonds involving the pyrrolidine groups as donors and both coordinate and uncoordinate nitrates as acceptors.     

Efficient P‐Chiral Biaryl Bisphosphorus Ligands for Palladium‐Catalyzed Asymmetric Hydrogenation

A series of structurally novel P‐chiral biaryl bisphosphorus ligands L1‐L5 (BABIBOPs) are developed, providing high efficiency for the first time in palladium‐catalyzed asymmetric hydrogenation of β‐aryl and β‐alkyl substituted β‐keto esters. With the Pd‐ L3 (iPr‐BABIBOP) catalyst, a series of chiral β‐hydroxyl carboxylic esters are formed in excellent enantioselectivities (up to>99% ee) and yields at catalyst loading as low as 0.01 mol%.     

Tandem Wittig – Reductive annulation decarboxylation approach for the synthesis of indole and 2-substituted indoles

A simple tandem Wittig reaction-reductive decarboxylation route is established for the synthesis of indoles from commercially available o-nitrobenzaldehydes and a stable phosphorane. The method allows access to indoles in a very fast manner without involving any metal or expensive reagents or inert atmosphere. Also 2-substituted indoles are obtained which forms an important core of many biological active compounds.     

One-pot Sonogashira coupling,hydroamination of alkyne and intramolecular CH arylation reactions toward the synthesis of indole-fused benzosultams

A one-pot Sonogashira coupling, hydroamination of alkyne and CH arylation reactions for the synthesis of indole-fused benzosultams are described. This method allows access to a variety of indole-fused seven membered benzosultams in good to excellent yields. The free indolyl nitrogen containing indole-fused benzosultams are also prepared by this method. The structures of the synthesized compounds are confirmed by single crystal XRD studies.     

新型3,5-二取代1H-吲哚衍生物的合成及抗肿瘤活性研究

新型抗肿瘤药物研究是全球药物开发的重点任务之一。鉴于前期我们发现3,5-二取代1H-吲哚衍生物具有明显抗胰腺癌活性,本文通过维尔斯迈尔-哈克反应、仲胺的叔丁氧羰基(Boc)保护、醛还原、羧酸与胺的缩合等反应获得了一条高效简洁的3-取代硫甲基-5-酰氨基吲哚衍生物合成路线,并合成了8个新化合物11a~11h。经细胞活性测试发现,它们对胰腺癌细胞株BxPC-3均有较好抑制活性,其中11e活性最高,IC_(50)为2.28μmol/L。对多种肿瘤细胞及人正常肝细胞HL-7702的抑制活性测试表明,11e为特异性BxPC-3抑制剂而非细胞毒化合物。鉴于此,11e可能是一个较好的抗胰腺癌苗头化合物,值得进一步深入研究。     

Synthesis of ReI tricarbonyl complexes with various sulfur‐ and oxygen‐donating ligands: crystal structures of two ReI dinuclear structures bridged by S atoms

The synthesis and characterization of two dinuclear complexes, namely fac‐hexacarbonyl‐1κ³C,2κ³C‐(pyridine‐1κN)[μ‐2,2′‐sulfanediyldi(ethanethiolato)‐1κ²S¹,S³:2κ³S¹,S²,S³]dirhenium(I), [Re₂(C₄H₈S₃)(C₅H₅N)(CO)₆], ( 1 ), and tetraethylammonium fac‐tris(μ‐2‐methoxybenzenethiolato‐κ²S:S)bis[tricarbonylrhenium(I)], (C₈H₂₀N)[Re₂(C₇H₇OS)₃(CO)₆], ( 2 ), together with two mononuclear complexes, namely (2,2′‐bithiophene‐5‐carboxylic acid‐κ²S,S′)bromidotricarbonylrhenium(I), ( 3 ), and bromidotricarbonyl(methyl benzo[b]thiophene‐2‐carboxylate‐κ²O,S)rhenium(I), ( 4 ), are reported. Crystals of ( 1 ) and ( 2 ) were characterized by X‐ray diffraction. The crystal structure of ( 1 ) revealed two Re—S—Re bridges. The thioether S atom only bonds to one of the Re^I metal centres, while the geometry of the second Re^I metal centre is completed by a pyridine ligand. The structure of ( 2 ) is characterized by three S‐atom bridges and an Re…Re nonbonding distance of 3.4879 (5) Å, which is shorter than the distance found for ( 1 ) [3.7996 (6)/3.7963 (6) Å], but still clearly a nonbonding distance. Complex ( 1 ) is stabilized by six intermolecular hydrogen‐bond interactions and an O…O interaction, while ( 2 ) is stabilized by two intermolecular hydrogen‐bond interactions and two O…π interactions.     

Access to the Bis‐benzene Cobalt(I) Sandwich Cation and its Derivatives: Synthons for a “Naked” Cobalt(I) Source?

The synthesis and structural characterization of the hitherto unknown parent Co(bz)₂⁺ (bz=benzene) complex and several of its derivatives are described. Their synthesis starts either from a CoCO₅⁺ salt, or directly from Co₂(CO)₈ and a Ag⁺ salt. Stability and solubility of these complexes was achieved by using the weakly coordinating anions (WCAs) [Al(OR^F)₄]^? and [F{Al(OR^F)₃}₂]^? {R^F=C(CF₃)₃} and the solvent ortho‐difluorobenzene (o‐DFB). The magnetic properties of Co(bz)₂⁺ were measured and compared in the condensed and gas phases. The weakly bound Co(o‐dfb)₂⁺ salts are of particular interest for the preparation of further Co^I salts, for example, the structurally characterized low‐coordinate 12 valence electron Co(P^tBu₃)₂⁺ and Co(NHC)₂⁺ salts.     

A Redox‐Active Bridging Ligand to Promote Spin Delocalization,High‐Spin Complexes,and Magnetic Multi‐Switchability

A dinuclear Co^II complex, [Co₂(tphz)(tpy)₂]ⁿ⁺ (n=4, 3 or 2; tphz: tetrapyridophenazine; tpy: terpyridine), has been assembled using the redox‐active and strongly complexing tphz bridging ligand. The magnetic properties of this complex can be tuned from spin‐crossover with T_1/2≈470 K for the pristine compound (n=4) to single‐molecule magnet with an S_T=5/2 spin ground state when once reduced (n=3) to finally a diamagnetic species when twice reduced (n=2). The two successive and reversible reductions are concomitant with an increase of the spin delocalization within the complex, promoting remarkably large magnetic exchange couplings and high‐spin species even at room temperature.     

The β‐Agostic Structure in (C5Me5)2Sc(CH2CH3): Solid‐State NMR Studies of (C5Me5)2Sc−R (R=Me,Ph, Et)

Multinuclear solid‐state NMR studies of Cp*₂Sc?R (Cp*=pentamethylcyclopentadienyl; R=Me, Ph, Et) and DFT calculations show that the Sc?Et complex contains a β‐CH agostic interaction. The static central transition ⁴⁵Sc NMR spectra show that the quadrupolar coupling constants (C_q) follow the trend of Ph≈Me>Et, indicating that the Sc?R bond is different in Cp*₂Sc?Et compared to the methyl and phenyl complexes. Analysis of the chemical shift tensor (CST) shows that the deshielding experienced by Cβ in Sc?CH₂CH₃ is related to coupling between the filled σ_C‐C orbital and the vacant orbital.     

A Planar‐Chiral Rhodium(III) Catalyst with a Sterically Demanding Cyclopentadienyl Ligand and Its Application in the Enantioselective Synthesis of Dihydroisoquinolones

The rapid development of enantioselective C?H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar‐chiral rhodium catalyst [(C₅H₂^tBu₂CH₂^tBu)RhI₂]₂ in two steps from commercially available [(cod)RhCl]₂ and tert‐butylacetylene. Pure enantiomers of the catalyst were obtained through separation of its diastereomeric adducts with natural (S)‐proline. The catalyst promoted enantioselective reactions of aryl hydroxamic acids with strained alkenes to give dihydroisoquinolones in high yields (up to 97 %) and with good stereoselectivity (up to 95 % ee).