The structure of castanaguyone a biisocoumarin plant product

The fruit extract of the Mexican shrub $\text{Zanthoxylum}$$\text{fagara}$ Sarg. has afforded castanaguyone $\text{1}$; it is the first biisocoumarin encountered in nature.     

Oxidation reactions of 3,4,5-triamino-1,2,6-thiadiazine 1,1-dioxide. Preparation of 3,5-diamino-4H-1,2,6-thiadiazin-4-one 1,1-dioxide

Oxidation reactions of 3,4,5-triamino-1,2,6-thiadiazine 1,1-dioxidc with hydrogen peroxide and chromium trioxide are reported. 3, 5-Diamino-4H-1,2,G-thiadiazin-4-one 1,1-dioxide is synthesized by different methods.     

Dopamine interaction in the absence and in the presence of Cu2+ ions with macrocyclic and macrobicyclic polyamines containing pyrazole units. Crystal structures of [Cu2(L1)(H2O)2](ClO4)4 and [Cu2(H-1L3)](ClO4)3*2H2O.

The interaction with Cu2+ and dopamine of three polyazacyclophanes containing pyrazole fragments as spacers is described. Formation of mixed complexes Cu2+-macrocycle-dopamine has been studied by potentiometric methods in aqueous solution. The crystal structures of the complexes [Cu2(L1)(H2O)2](ClO4)4*2H2O (4) (L1 = 13,26-dibenzyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo[22.2.1.1(11,14)]octacosa-1(27),11,14(28),24-tetraene) and [Cu2(H-1L3)](HClO4)(ClO4)2*2H2O (6) (L3 = 1,4,7,8,11,14,17,20,21,24,29,32,33,36-tetradecaazapentacyclo[12.12.12.1(6,9).1(19,22).1(31,34)]hentetraconta-6,9(41),19(40),21,31,34(39)-hexaene) are presented. In the first one (4), each Cu2+ coordination site is made up by the three nitrogens of the polyamine bridge, a sp2 pyrazole nitrogen and one water molecule that occupies the axial position of a square pyramid. The distance between the copper ions is 6.788(2) A. In the crystal structure of 6, the coordination geometry around each Cu2+ is square pyramidal with its base being formed by two secondary nitrogens of the bridge and two nitrogen atoms of two different pyrazolate units which act as exobidentate ligands. The axial positions are occupied by the bridgehead nitrogen atoms; the elongation is more pronounced in one of the two sites [Cu(1)-N(1), 2.29(2) A; Cu(2)-N(6), 2.40(1) A]. The Cu-N distances involving the deprotonated pyrazole moieties are significantly shorter than those of the secondary nitrogens. The Cu(1)...Cu(2) distance is 3.960(3) A. The pyrazole in the noncoordinating bridge does not deprotonate and lies to one side of the macrocyclic cavity. One of the aliphatic nitrogens of this bridge is protonated and hydrogen bonded to a water molecule, which is further connected to the sp2 nitrogen of the pyrazole moiety through a hydrogen bond. The solution studies reveal a ready deprotonation of the pyrazole units induced by coordination to Cu2+. In the case of L2 (L2 = 3,6,9,12,13,16,19,22,25,26-decaazatricyclo[22.2.1.1(11,14)]octacosa-1(27),11,14(28),24-tetraene), deprotonation of both pyrazole subunits is already observed at pH ca. 4 for 2:1 Cu2+:L2 molar ratios. All three free receptors interact with dopamine in aqueous solution. L3 is a receptor particularly interesting with respect to the values of the interaction constants over five logarithmic units at neutral pH, which might suggest an encapsulation of dopamine in the macrocyclic cage. All three receptors form mixed complexes Cu2+-L-dopamine. The affinity for the formation of ternary dopamine complexes is particularly high in the case of the binuclear Cu2+ complexes of the 1-benzyl derivative L1.     

Ethyl methyl 1,4‐dihydro‐4‐(3‐nitrophenyl)‐2,6‐bis(1‐piperidylmethyl)­pyridine‐3,5‐dicarboxylate

In the title compound, C₂₈H₃₈N₄O₆, the 4‐aryl substituent occupies a pseudo‐axial position approximately orthogonal to the plane of the di­hydro­pyridine ring [88.1 (3)°]. The di­hydro­pyridine ring adopts a flattened boat conformation. The H atom on the pyridine N atom is involved in a bifurcated intramolecular hydrogen bond, the acceptors being the N atoms of the two piperidyl­methyl groups [N?N 2.629 (4) and 2.695 (4) Å].     

Laser‐micromachined cellulose acetate adhesive tape as a low‐cost smart material

An off‐the‐shelf, moisture‐responsive, acetate‐backed adhesive tape is investigated as a commercially available smart material for fabricating low‐cost, multifunctional, humidity‐responsive millimeter‐scale structures. Laser ablation is used for cutting and thinning‐down the tape to enhance its response. Water‐submerged cantilevers show a radius of curvature of 3 mm or lower (for laser‐thinned cantilevers). Additionally, their humidity response is a function of the angle between the longitudinal axis of the cantilever and polymer orientation. A cut angled at 80° with respect to this orientation results in a tip rotation of up to 25°, enabling the formation of bending cantilevers with twisting behavior. The tape cantilevers are further functionalized with magnetic nanoparticles and used to create four‐finger grippers that close underwater within minutes and can sample 100 µL of liquid. A cyclic humidity monitor is also fabricated using a tape strip that walks unidirectionally on a ratchet‐shaped surface upon exposure to humidity variations. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1263–1267     

About partial boundary dissipation to Timoshenko system with delay

We consider the Timoshenko model with partial dissipative boundary condition with delay, and we prove that the solution decays exponentially to zero, provided the wave speed are equal; this improve earlier result due to Bassam et al and Muñoz Rivera and Naso. Moreover, consider the exponential stability to the corresponding semilinear problems.     

Enantioselective Total Synthesis of (−)‐Diversonol

For the synthesis of (?)‐diversonol (ent‐ 1 ), an enantioselective domino‐Wacker/carbonylation/methoxylation reaction and an enantioselective Wacker oxidation were used to give the chroman in high yield and 96 % and 93 % ee, respectively. Dihydroxylation at the vinyl moiety using the Sharpless procedure and a Wittig–Horner reaction followed by hydrogenation, benzylic oxidation, and an intramolecular acylation provided the tetrahydroxanthenone, from which ent‐ 1 is accessible in a few steps. Furthermore, the synthesis of the diastereomeric diversonol rac‐1,9 a‐epi‐diversonol (rac‐ 41 ) is also described.     

A new type of reaction between o-phenylenediamines and aromatic aldehydes to give 2,3-diarylquinoxalines

A new type of reaction between o-phenylenediamines and aryl aldehydes at high temperature is reported. The synthesis of 2,3-diarylquinoxalines by this procedure is described.