Volume 65, Issue 2

Investigation of the fruits of Schisandra sphenanthera led to the isolation of two new dibenzocyclooctadiene lignans, methylgomisin O (1) and chloromethyl schisantherin B (2), together with twelve known lignans (3 - 14). Their structures were elucidated by using extensive spectroscopic techniques including 1D and 2D NMR spectra. Compound 2 was identified as a cyclooctadiene moiety substituted with a chloromethyl group, which is rarely found in natural products, especially in terrestrial higher plants. Among these isolates, compounds 1 and 7 exhibited considerable inhibitory activity against tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) production, and did not display any cellular toxicity against RAW264.7 cells. Graphical Abstract New Dibenzocyclooctadiene Lignans from Schisandra sphenanthera and Their Proinflammatory Cytokine Inhibitory Activities

The reaction of CpML 2 Cl (M = Fe, L = CO; M = Cr, L = NO) with benzil diimine (H 2 BDI) (2) derived from benzil-bis(trimethylsilyl)diimine (Si 2 BDI) (1) in a 1 : 3 and 1 : 2 molar ratio in the presence of excess AgO 3 SCF 3 (= AgOTf) resulted in the formation of the new cationic tris- and bisbenzildiimine complexes [Fe(H 2 BDI) 3 ]X 2 (3) and [CpCr(H 2 BDI)2]X 2 (X = OTf) (4), respectively. The addition of AgO 3 SCF 3 is necessary in both cases to abstract chloride. Unusual in the first case is the total replacement of ligands of CpFe(CO) 2 Cl and in the second case the oxidation of Cr(0) to Cr(III) leading to the formation of complexes 3 and 4, respectively, with the neutral bidentate diimine ligand 2. Complexes 3 and 4 were fully characterized by their IR, mass, 1 H- and 13 C-NMR spectra, as well as elemental analyses. The molecular structures determined by X-ray diffraction studies reveal a distorted octahedral tris-chelate configuration in 3 and a pseudo-tetragonal pyramidal one in 4. Graphical Abstract Formation of the Complexes [Fe(H 2 BDI) 3 ]X 2 and [CpCr(H 2 BDI) 2 ]X 2 (X =OTf) fromthe Unusual Reactions of Benzil-bis(trimethylsilyl)diimine with CpML 2 Cl (M = Fe, L = CO; M = Cr, L = NO)

Lithium-tert-butylmethylhydrazonide II, Me 3 C(Me)C=N-NHLi, reacts with F 2 Si[N(CHMe 2 ) 2 ] 2 to give Me 3 C(Me)C=N-NH-SiF[N(CHMe 2 ) 2 ] 2 1. The lithium salt of 1, Me 3 C(Me)C=N- N(Li)SiF[N(CHMe 2 ) 2 ] 2 , 1a, prepared in the reaction of 1 with n-C 4 H 9 Li, is substituted with F 2 BN(SiMe 3 ) 2 forming Me 3 C(Me)C=N-NBFN(SiMe 3 ) 2 SiF[N(CHMe 2 ) 2 ] 2 , 2. Experiments to synthesise the silaketazine, Me 3 C(Me)C=N-N=Si[N(CHMe 2 ) 2 ], III, via LiF-elimination from 1a lead to the intramolecular formation of an N-functional 1,2-diaza-3-silacyclopentene, H 2 C-C(CMe 3 )=N- NHSi[N(CHMe 2 ) 2 ] 2 , 3, which is a structural isomer of III. The NH unit of 3 can be lithiated with n-C 4 H 9 Li. The lithium salt reacts with F 2 BN(SiMe 3 ) 2 forming the substituted ring compound 4. The rearrangement of the silaketazine III to the ring compound 3 is described by density functional calculations predicting a three-step reaction mechanism correlated with the experimental data. The structures of 3 and 4 are discussed in detail. Graphical Abstract Thermische Isomerisierung eines Silenketazins zum Diazasilacyclopenten: Experimentelle und theoretische Untersuchungen

The molecular structures of three alkynylsilanes, tetrakis(ethynyl-p-tolyl)silane, 3,3,6,6,-tetramethyl- 3,6-disila-triyne, 3,3,6,6,9,9,-hexamethyl-3,6,9-trisila-tetrayne, and of bis(trimethylstannyl)- ethyne have been determined by X-ray diffraction. The same alkynylsilanes, and in addition 1,2- bis(trimethylsilylethynyl)-1,1,2,2-tetramethyldisliane, were studied by solid-state 13 C and 29 Si MAS NMR spectroscopy. The results of these measurements were compared with crystallographic evidence and also with relevant solution-state NMR data. Graphical Abstract Tetra(alkynyl)silanes, a 3,6-Disila-triyne, a 3,6,9-Trisila-tetrayne, a 1,3,4,6-Tetrasiladiyne, and Bis(trimethylstannyl)ethyne. Molecular Structures and Solid-state NMR Studies

Three substituted 2,2'-bipyridine adducts of lead(II) thenoyltrifluoroacetonate, [Pb(4,4'-dm-2,2’- bpy)(ttfa) 2 ] 2 , 1, [Pb(5,5' -dm-2,2’-bpy)(ttfa) 2 ] 2 , 2, and [Pb(4,4'-dmo-2,2’-bpy)(ttfa) 2 ], 3, (4,4’ -dm- 2,2’-bpy, 5,5’-dm-2,2’-bpy, 4,4’-dmo-2,2’-bpy and ttfa are the abbreviations for 4,4’-dimethyl-, 5,5’-dimethyl-, and 4,4’-dimethoxy-2,2’-bipyridine, and thenoyltrifluoroacetonate, respectively) have been synthesized, characterized by elemental and thermal analysis, IR and 1 H- and 13 C-NMR spectroscopy, and studied by X-ray crystallography. The supramolecular features in these complexes are guided/controlled by weak directional intermolecular interactions. Graphical Abstract Synthesis and Crystal Structure of Lead(II) Thenoyltrifluoroacetonate Complexes with Substituted 2,2' -Bipyridines: Interplay of Intermolecular Interactions in Crystals

A novel supramolecular compound based on the Keggin polyoxometalate (Hpipz) 3 [PMo 12 O 40 ](1) (pipz = piperazine) has been synthesized and characterized. X-Ray diffraction analysis reveals that the Keggin polyanion uses all of its surface oxygen atoms (36) to attract eighteen pipz units at its periphery. This represents the highest connectivity of a Keggin polyoxoanion. The electrochemical behavior of a CPE modified with 1 (1-CPE) has been studied. Graphical Abstract Supramolecular Assembly through the Highest Connectivity of a Keggin Polyoxometalate

Two kinds of multilayer films based on Keggin polyoxometalates α-[SiW 12 O 40 ] 4− /α- [PMo 12 O 40 ] 3− and methylene blue have been prepared via the layer-by-layer (LBL) self-assembly technique. The multilayer films were characterized by UV/Vis spectra, atomic force microscopy (AFM) and X-ray photoelectron spectra (XPS). The cyclic voltammetry (CV) measurements have demonstrated that the electrochemical properties of POMs are maintained in the LBL films. The antibacterial activity of the LBL films has also been investigated, which shows a distinct antibacterial effect against Escherichia coli. Graphical Abstract Fabrication and Characterization of Antibacterial-active Multilayer Films Based on Keggin Polyoxometalates and Methylene Blue

Titanium tetra-butoxide was reacted with dichloroacetic acid in 1 : 1 and 1 : 2 molar ratio in toluene at ambient temperature to give, respectively, the mono- and bis-substituted products Ti(OBu n ) 3 (OOCCHCl 2 ) and Ti(OBu n ) 2 (OOCCHCl 2 ) 2 (1) in quantitative yields. However, when a toluene solution of compound 1 was kept at −20 ◦C for crystallisation, colourless crystals of a hexanuclear complex Ti 6 (μ 2 -O) 2 (μ 3 -O) 2 (μ 2 -OC 4 H 9 ) 2 (OC 4 H 9 ) 6 (OOCCHCl 2 ) 8 (2) were obtained. The basic skeletal arrangement of compound 2, as revealed by X-ray diffraction, can be described as corner-removed, inversion-related [Ti-O] 4 cubes with face-linked oxide bridges. Graphical Abstract Synthesis and Structural Characterisation of a Hexanuclear Ti IV Compound Ti 6 (μ 2 -O) 2 (μ 3 -O) 2 (μ 2 -OC 4 H 9 ) 2 (OC 4 H 9 ) 6 (OOCCHCl 2 ) 8

A new three-dimensional (3D) supramolecular framework, [Ag 2 (bipy) 2 (bdc)·4H 2 O] n 1, has been synthesized by the ultrasonic reaction of Ag 2 O, bipy and H 2 bdc (H 2 bdc = 1,4-benzenedicarboxylic acid; bipy = 4,4’-bipyridine) at room temperature. It exhibits a new 3D supramolecular framework which is built from cationic Ag-bipy chains and anionic bdc-H 2 O sheets through hydrogen bonds, π · · ·π stacking and C-H· · ·π interactions. Additionally, the photoluminescent and thermal properties of 1 were investigated. Graphical Abstract Self-assembly of a Novel Three-dimensional Silver(I) Supramolecular Framework from Cationic Chains and Anionic Sheets

In the crystal structure of the title complex, K 2 [(VO) 2 (NH 2 O) 4 (C 3 H 2 O 4 ) 2 ] ・ 3H 2 O, the V(V) centre is bound to a chelating malonate ligand, two bidentate hydroxylamido ligands and one oxo ligand, defining a pentagonal bipyramidal coordination (VO 5 N 2 ). The potassium cations are found to adopt two types of coordination geometry with the malonate ligand, the bidentate hydroxylamido ligand and water molecules: the first one is hepta-coordinate in an irregular K(1)O7 polyhedron, and the second one is octa-coordinate in an irregular K(2)O 8 polyhedron. The K(1)O 7 /K(2)O 8 and VO 5 N 2 polyhedra are closely linked by sharing faces to form K-V dinuclear units KVO 9 N 2 and KVO 10 N 2 , respectively. The two close-packed units, KVO 9 N 2 and KVO 10 N 2 , are connected by sharing edges to generate a tetrameric unit K 2 V 2 O 17 N 4 . Each of these units is joined to four neighbouring units by sharing corners, providing further propagation into a two-dimensional layer. Adjacent layers are connected via the carboxylic oxygen atoms of the malonate units to give a three-dimensional framework in the crystals. Graphical Abstract Synthesis and Crystal Structure of the Novel Three-dimensional Vanadium Coordination Compound Potassium Oxo-bis(hydroxylamido)malonatovanadate(V)

A new organic-inorganic hybrid molybdoarsenate constructed from a unit with two (As 3 O 3 ) rings capping Anderson-type moieties, [Cu(en) 2 ] 2 [(CuO 6 )Mo 6 O 18 (As 3 O 3 ) 2 ] (1) (en = ethylenediamine), has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction and thermogravimetric analysis. The compound crystallizes monoclinically, space group P2 1/c , with unit cell dimensions a = 9.1541(7), b = 19.6348(14), c = 14.5205(8) Å ,β = 129.082(3)◦,V = 364.20(4) Å 3 , Z = 2, T = 296(2) K. Complex 1 represents the first example of a 2D network of a POM polymer where [(CuO 6 )Mo 6 O 18 (As 3 O 3 ) 2 ] 4− building blocks are connected by complex fragments {Cu(en) 2 } 2+ . Graphical Abstract Synthesis and Structural Characterization of a New Two-dimensional Organic-Inorganic Hybrid Molybdoarsenate: [Cu(en) 2 ] 2 [(CuO 6 )Mo 6 O 18 (As 3 O 3 ) 2 ]

A convenient system for producing 5-hydroxymethylfurfural (HMF) through dehydration of carbohydrates by microwave heating in the presence of ZnCl 2 was studied. The use of ZnCl 2 gave higher selectivity than other metal salts in the conversion of glucose. With ZnCl 2 as catalyst, sucrose could be utilized effectively. Under the conditions of microwave irradiation (300 W, 8 min), HMF yields were 54.6, 55.1, and 80.6% from glucose, fructose and sucrose, whereas upon conventional oil bath heating (0.11 gmL −1 sugar solution, weight ratio of ZnCl 2 to substrate = 1 : 4, 189 °C, 60 min) HMF yields from glucose, fructose and sucrose were only up to 37.7, 42.7, and 57.7%, respectively. Graphical Abstract Microwave-assisted Conversion of Carbohydrates into 5-Hydroxymethylfurfural Catalyzed by ZnCl 2

The 1 : 1 reaction of 3,5-dimethyl-1,2,4,3,5-trithiadiborolane, 3, with dimethylamine in diethyl ether yielded a mixture of compounds from which only MeB(NMe 2 )SH, 7, could be separated. In the 1:2 reaction, insoluble Me 2 NH(MeB(S 2 ) 2 BMe)HNMe 2 , 10, could be isolated besides 7 and small amounts of MeB(NMe 2 ) 2 . In the presence of NMe 3 the bis(methyl-dimethylamino-boryl)sulfide, 7 was obtained in good yield. Replacement of HNMe 2 by N-methylaniline or piperidine led to the corresponding amino(methyl)sulfhydrido boranes R 2 N(MeB)SH in moderate yields. tBuNH(MeB)SH results in 61% yield from the treatment of tBu 2 B 2 S 3 with tBuNH 2 in a 1 : 1 ratio. Graphical Abstract Reactions of 3,5-Dimethyl-1,2,4,3,5-trithiadiborolane with Secondary Amines: Formation of Diorganylamino(sulfhydryl)boranes

A series of 3,6-disubstituted [1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 5a - l bearing an adamantyl moiety were synthesized by condensation of 4-amino-5-aryl-2H-1,2,4-triazole-3(4H)-thiones 4a -l with adamantyl-1-carboxylic acid in the presence of POCl 3 . The structures of the newly synthesized compounds were established using spectroanalytical techniques and verified further by the crystal structure determination of compounds 5a and 5j. The compounds were screened for their antiproliferative activity against a large panel of human cell lines. Graphical Abstract Synthesis, Crystal Structure and Antiproliferative Activity of 6-Adamantyl-3-aryl[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles

(E)-N-(4-Nitrobenzylidene)-3,4-dimethylaniline (1) and (E)-N-(3-nitrobenzylidene)-3,4-dimethylaniline (2) have been synthesized, and their crystal structures have been determined by X-ray diffraction analysis. Linear optical characteristics have been evaluated experimentally using UV/Vis spectroscopy and theoretically using the configuration interaction (CI) method. The maximum onephoton absorption (OPA) wavelengths of the studied compounds are shorter than 450 nm, giving rise to good optical transparency in the visible and near IR regions. The ab initio quantum-mechanical calculations (finite field second-order Møller-Plesset perturbation theory) of the investigated molecules have been carried out to compute the electric dipole moment (μ) and the first hyperpolarizability (β ) values. The ab initio results suggest that the title compounds might have microscopic second-order nonlinear optical (NLO) behavior with non-zero values. Graphical Abstract Syntheses, Structures and Second-order Nonlinear Optical Behavior of (E)-N-(4-Nitrobenzylidene)-3,4-dimethylaniline and (E)-N-(3-Nitrobenzylidene)-3,4-dimethylaniline

The tricyclic oxazolidines trans-4 and cis-4 were interconverted upon treatment with allyltrimethylsilane/ TiCl 4 . The oxazolidine trans-4 was diastereoselectively reacted with PhMgBr to yield the 4,4-disubstituted 3-benzazepinone 6, along with two side products. An X-ray crystal structure analysis of 6 proved the (R)-configuration of the stereogenic center C-4 and thus the retention of configuration. Reduction of 6 with AlCl 3 /LiAlH 4 (1/3) followed by hydrogenolysis with H 2 , Pd/C resulted in the formation of enantiomerically pure 2-methyl-2-phenyl-tetrahydro-3-benzazepine 11 which has a moderate affinity (K i = 496 nM) to the PCP binding site of the NMDA receptor. Graphical Abstract Enantioselective Synthesis of a 2,2-Disubstituted Tetrahydro-3- benzazepine as Novel NMDA Receptor Antagonist

Ring-opening addition reactions of 1-tert-butoxycarbonyl-3,4-epoxypiperidine leading to the formation of the corresponding regioisomeric trans-β -aminoalcohols were carried out with three different types of amine nucleophiles under different reaction conditions with a view to study the reactivity and regioselectivity. Graphical Abstract Ring-opening Addition Reactions of 1-tert-Butoxycarbonyl-3,4- epoxypiperidine with Amine Nucleophiles

Reinvestigation of the flowers of Alstonia scholaris of Pakistan origin have resulted in the isolation of three new triterpenoids, two of the ursane type, 3β -acetate-24-nor-urs-4,12-diene ester triterpene (1) and 3β -hydroxy-24-nor-urs-4,12,28-triene triterpene (2), and one of the oleanane type, 3,28-β - diacetoxy-5-olea-triterpene (3), together with two known triterpenes,α-amyrin acetate (4) and ursolic acid (5). This is the first report of the isolation of 4 and 5 from the flower part of this species. The structures of 1 - 5 were elucidated with the aid of extensive NMR-spectroscopic studies. Graphical Abstract Phytochemical Studies on Alstonia scholaris