First total synthesis of paecilodepsipeptide A

The first total synthesis of paecilodepsipeptide A is reported.A convergent,flexible strategy employing peptide chemistry and culminating in macrolactamisation is described.The previously reported structure of compound is confirmed.     

Highly sensitive silicon carrier-domain magnetometer

A novel, vertically structured, silicon carrier-domain magnetometer is described.¹ The magnetometer sensitivity (0.3 υA per G with a current drive of 10 mA and a noise level of 50 mG) is larger than reported previously for silicon magnetic sensors. The device is analysed and three operating modes are reported. These modes produce current, voltage and frequency outputs, respectively.     

The enantioselective halo aldol reaction utilizing cyclopropyl ketone-derived enolates

A new enantioselective halo aldol reaction is reported using a chiral borane catalyst. The absolute stereochemistry of the product was unambiguously determined by chemical transformations and a preliminary mechanistic study is reported.     

Oxidation products of VO(T(m-NO2)PP): EPR and cyclic voltammetric studies

The EPR study of VO(T(m-NO2)PP)+ at 77 K is reported. A triplet state spectrum of VO(T(m-NO2)PP)(+) at 77 K is obtained. The ZFS parameters are obtained from the computer simulation. An inter-electron distance of 3.57+/-0.05 A between the two unpaired electrons is obtained. This is attributed to an a(2u) ground state of the porphyrin. Also, room temperature EPR of the pre-oxidized species of VOTPP with SbCl5 are reported. The effect on the oxidation potentials due to substitution is also reported.     

TTF‐TCNQ Functionalized Ormosil Based Electrocatalytic Biosensor: A comparative study on Bioelectrocatalysis

A novel electrocatalytic biosensor for glucose is reported that incorporate encapsulation of tetrathifulvalene‐tetracyanoquinodimethane (TTF‐TCNQ) functionalized organically modified sol gel glass (ormosil). The new ormosil is made using palladium‐linked glycidoxypropyltrimethoxysilane precursor, trimethoxysilane, HCl and TTF‐TCNQ powder at 25 °C. The ormosil is converted into fine powder and incorporated within graphite paste electrode along with glucose oxidase. The bioelectrochemistry of GOD and TTF‐TCNQ functionalized ormosil is examined based on cyclic voltammetry and amperometric measurements. A large electrocatalytic current to the order of 8000 μA/cm² is recorded on the addition of 300 mM glucose. Typical responses of new biosensor are reported. The sensitivity of glucose analysis is found relatively much better as compared to earlier reported glucose biosensors. The role of palladium and TTF‐TCNQ introduction within ormosil and its advantages on bioelectrocatalysis are discussed.     

Design of new synthetic strategies to cyclophanes via ring-closing metathesis

A simple synthetic methodology to cyclophanes containing hydroxyl groups has been reported. The key steps involved here are: Grignard reaction, double Claisen rearrangement, and ring-closing metathesis. The strategy reported here is protecting group-free synthesis.     

Efficient “on water” green route heterocyclization of thiosemicarbazones with DMAD

A simple, efficient, and eco-friendly procedure for the synthesis of thiazolidin-4-one derivatives in water from cyclocondensation reaction of thiosemicarbazone derivatives and dimethylacetylene dicarboxylate (DMAD) in good yield is reported. The regiochemistry of the cyclized products is established by elemental analysis, IR, NMR, and mass spectral data. A single crystal X-ray diffraction study of a representative compound, 3f, is reported.     

2,5,8,11-Tetraboronic ester perylenediimides: a next generation building block for dye-stuff synthesis

Via an unprecedentedly reported ruthenium catalyzed reaction, an efficient and straightforward method was developed for the synthesis of 2,5,8,11-tetraboronate perylenediimide derivatives. A possible reaction mechanism is proposed. The synthesis of 2,5,8,11-tetra-iodo and tetra-amino perylenediimides derivatives is also reported.     

Liquid Droplet excitation of freestanding poly(methyl methacrylate)/graphene oxide films for mechanical energy harvesting

A simple and solvent‐free practical way to obtain freestanding poly(methyl methacrylate)/graphene oxide films is reported. Falling liquid droplets are used to produce an impulse necessary for the mechanical excitation of such composite films. A pressure wave is generated on the surface of the films by the impact. It is reported how such films are able to convert mechanical energy of the impact to electrical power. The reported example is of interest to enhance the mechanical energy harvesting and to add new functionalities to traditional polymer nanocomposites. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1028–1032     

Mild Pd-catalyzed N-arylation of methanesulfonamide and related nucleophiles: avoiding potentially genotoxic reagents and byproducts

A convenient, general, and high yielding Pd-catalyzed cross-coupling of methanesulfonamide with aryl bromides and chlorides is reported. The use of this method eliminates concern over genotoxic impurities that can arise when an aniline is reacted with methanesulfonyl chloride. The application of this method to the synthesis of dofetilide is also reported.     

Determination of subnanogram amounts of chromium in different matrices by flameless atomic-absorption spectroscopy

A carbon rod flameless atomizer is used for the determination of Cr in water, sea-water, sugar, glycine and blood. The reported analytical curves show that the quantitative determination of Cr in these matrices is feasible in the ppM-ppm range. The influence of the most common anionic and cationic interferents is reported.     

Palladium(0)-catalyzed highly regio- and stereoselective addition of organoboronic acids with 1,2-allenylphosphonates forming tri- or tetrasubstituted 1(E)-alkenylphosphonates

A highly regio- and stereoselective palladium(0)-catalyzed addition of organoboronic acids with 1,2-allenylphosphonates in the presence of HOAc forming tri- or tetrasubstituted 1(E)-alkenylphosphonates is reported in this paper. The stereoselectivity is much higher than the reported cases. The effects of different R(1), R(2), and R(3) were studied. A mechanism of this reaction is proposed on the basis of our previous study.     

Synthesis of 6,6'-Binaphthopyran-2-one Natural Products: Pigmentosin A, Talaroderxines A and B

Efficient and stereoselective syntheses of pigmentosin A, talaroderxine A, and its diastereomer talaroderxine B are reported. The binaphthyl ring system is assembled by vanadium-catalyzed phenolic coupling of tricyclic precursors. These key intermediates were prepared by Michael-Dieckmann annulation of a protected orsellinate ester, with the requisite pyranones accessed by a new variant of Ghosez's sulfone-epoxide annulation. Preliminary biological experiments are reported for pigmentosin.     

Synthesis and study of the antimalarial cardamom peroxide

A full account of our previously disclosed synthesis of the monoterpene dimer cardamom peroxide is reported. Inspired by hypotheses regarding the potential biosynthetic origins of this natural product, several unproductive routes are also reported. The chemical reactivity of this structurally unique metabolite in the presence of iron (II) sources is also reported as is its antimalarial activity against Plasmodium falciparum clinical isolates from several Cambodian provinces.     

PLASMA POLYMERIZATION OF ACETYLENE/CO_2/H_2

A study has been made on the plasma polymerization of acetylene/CO_2/H_2 in a capacitively coupled RF plasma. The monomer mixture yielded a crosslinked film with light brown color. A kinetic study is reported for the plasma polymer ization of acetylene/CO_2/H_2. The effects of discharge power level and reactor geometry on the rate of polymer formation are reported. The structure of the plasma polymer is investigated by IR study.     

New heterogeneous catalyst for enantioselective borane reduction of ketones: phosphinamide anchored to nickel boride

A new example of heterogenization of a homogeneous catalyst by anchoring the chiral molecule to nickel boride is reported. The enantioselectivity in the reduction of acetophenone reaches that reported under homogeneous conditions.     

A Convenient Synthesis of Aromatic-Ring-Substituted Diacetylenes

A simple and convenient way for the preparation of symmetrical diarylbutadiynes 5 with improved yields is reported (Scheme 2). The reaction time is drastically reduced using this method compared to previously reported procedures.     

Metal–Metal Distances at the Limit: Cr–Cr 1.73 Å – the Importance of the Ligand and its Fine Tuning

The synthesis and structure of a homobimetallic chromium complex is reported. The ligand used to stabilise the quintuply bonded metals is a sterically fine‐tuned guanidinate. A chromium–chromium bond length of 1.7293(12) Å was observed. It is the shortest metal–metal distance reported for a stable compound yet.     

Organosilicon compounds VI. The preparation of silylaziridines and silyldiaziridines by silicon-carbon cleavage

The preparation of several 2-furyl-, 2-thienyl-, benzyl-, and allylsubstituted silanes is reported. Such derivatives, when treated with aziridine in the presence of a metal catalyst, afford good yields of silylaziridines and silyldiaziridines. A qualitative study of electronic and steric requirements of the displacement reaction is reported.     

Synthesis of polyacetylenic montiporic acids A and B

The synthesis of two polyacetylenic acids, montiporic A and B is reported.