Relations on the period mapping giving extensions of mixed hodge structures on compact Riemann surfaces

We consider a period map from Teichmüller space to , which is a real vector bundle over the Siegel upper half space. This map lifts the Torelli map. We study the action of the mapping class group on this period map. We show that the period map from Teichmüller space modulo the Johnson kernel is generically injective. We derive relations that the quadratic periods must satisfy. These identities are generalizations of the symmetry of the Riemann period matrix. Using these higher bilinear relations, we show that the period map factors through a translation of the subbundle and is completely determined by the purely holomorphic quadratic periods. We apply this result to strengthen some theorems in the literature. One application is that the quadratic periods, along with the abelian periods, determine a generic marked compact Riemann surface up to an element of the kernel of Johnson's homomorphism. Another application is that we compute the cocycle that exhibits the mapping class group modulo the Johnson kernel as an extension of the group SP _g () by the group .     

First total synthesis of (+/-)-strychnofoline via a highly selective ring-expansion reaction

An efficient synthesis of the antitumor alkaloid (+/-)-strychnofoline is documented. Key to the development of the highly convergent strategy delineated is the coupling of a cyclic imine with spiro[cyclopropan-1,3'-oxindole], which takes place in a highly diastereoselective manner. The ability to conduct annulation reactions of spirocyclopropyloxindoles with functionalized cyclic imines provides new avenues for the preparation of this important class of biologically active structures.     

Simultaneous multichannel mass-specific detection for high-performance liquid chromatography using an array detector sector-field mass spectrometer

The use of a separation step, such as liquid chromatography, prior to inductively coupled plasma mass spectrometry (ICP–MS) has become a common tool for highly selective and sensitive analyses. This type of coupling has several benefits including the ability to perform speciation analysis or to remove isobaric interferences. Several limitations of conventional instruments result from the necessity to scan or pulse the mass spectrometer to obtain a complete mass spectrum. When the instrument is operated in such a non-continuous manner, duty cycle is reduced, resulting in poorer absolute limits of detection. Additionally, with scanning instruments, spectral skew can be introduced into the measurement, limiting quantitation accuracy. To address these shortcomings, a high-performance liquid chromatograph has been coupled to an ICP–MS capable of continuous sample introduction and simultaneous multimass detection. These features have been realized with a novel detector array, the focal plane camera. Instrument performance has been tested for both speciation analysis and for the elimination of isobaric interferences. Absolute limits of detection in the sub picogram to tens of picograms regime are obtainable, while the added mass dimension introduced by simultaneous detection dramatically increases chromatographic peak capacity.     

The Mitsunobu Reaction: Origin,Mechanism, Improvements,and Applications

The Mitsunobu reaction is a widely used and versatile method for the dehydrative oxidation–reduction condensation of an acid/pronucleophile usually with a primary or secondary alcohol that requires the combination of a reducing phosphine reagent together with an oxidizing azo reagent. The utility of this reaction stems from the fact that it is generally highly stereoselective and occurs with inversion of the stereochemical configuration of the alcohol starting material. Furthermore, as carboxylic acids, phenols, imides, sulfonamides, and other compounds can be used as the acid/pronucleophile, this reaction is useful for the preparation of a wide variety of functional groups. This Focus Review of the Mitsunobu reaction summarizes its origins, the current understanding of its mechanism, and recent improvements and applications.     

Catalytic asymmetric synthesis with rh-diene complexes: 1,4-addition of arylboronic acids to unsaturated esters

A general route to enantioenriched tert-butyl 3,3-diarylpropanoates is presented. These useful building blocks are prepared via an asymmetric rhodium-catalyzed conjugate addition of arylboronic acids to unsaturated tert-butyl esters in the presence of chiral dienes as ligands. The addition of both electron-poor and electron-rich boronic acids proceeds smoothly with various enoates in 63-90% yield with high enantioselectivites (89-94% ee). [reaction: see text]     

Channel activity of a viral transmembrane peptide in micro-BLMs: Vpu(1-32) from HIV-1

We report for the first time on pore-suspending lipid bilayers, which we call micro-black lipid membranes (micro-BLMs), based on a highly ordered macroporous silicon array. Micro-BLMs were established by first functionalizing the backside porous silicon surface with gold and then chemisorbing 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol followed by spreading 1,2-diphytanoyl-sn-glycero-3-phosphocholine dissolved in n-decane. Impedance spectroscopy revealed the formation of single lipid bilayers confirmed by a mean specific capacitance of 0.6 +/- 0.2 microF/cm2. Membrane resistances were in the G omega-regime and beyond. The potential of the system for single channel recordings was demonstrated by inserting the transmembrane domain of the HIV-1 accessory peptide Vpu(1-32), which forms helix bundles with characteristic opening states. We elucidated different amilorides as potential drugs to inhibit channel activity of Vpu.     

Cobalt-catalyzed hydrohydrazination of dienes and enynes: access to allylic and propargylic hydrazides

[reaction: see text] The cobalt-catalyzed hydrohydrazination reaction of dienes and enynes is presented. Allylic and propargylic hydrazines were obtained in synthetically useful yields (allylic amines, 60-90%; propargylic amines, 47-83%) and good chemo- and regioselectivity.     

Novel Hydrogen‐bond Three Dimensional Networks Generated from the Reaction of Metal Nitrate Hydrate (M = Co,Ni) with Ammonium Thiocynate and Bidentate Ligand Piperazine

The reaction of Co(NO₃)₂·6H₂O with two equivalents of PPz (PPz = piperazine hexahydrate) and two equivalents of NH₄SCN in CH₃OH afforded the complex [Co(NCS)₂(PPz)₂(CH₃OH)₂]. The reaction of Ni(NO₃)₂·6H₂O with two equivalents of PPz and four equivalents of NH₄SCN in CH₃OH afforded the complex [Ni(NCS)₄(PPz)₂]. Their IR spectra have been recorded and the structures have been determined. Crystal data for 1 : space group P&1bar;, a = 6.7208(6) Å, b = 8.4310(8) Å, c = 8.5923(8) Å, a = 77.881(2)°, β = 76.342(2)°, γ = 83.936(2)°, V = 461.75(1) ų, Z = 1 with final residuals R1 = 0.0650 and wR2 = 0.1725. Crystal data for 2 : space group P2(1)/n, a = 7.4209(6) Å, b = 11.0231(9) Å, c = 12.317(1) Å, β = 96.642(9)°, V = 1000.9(2) ų, Z = 2 with final residuals R1 = 0.0378 and wR2 = 0.0809. Important NCS—H‐N and O‐H—N(PPz) hydrogen‐bonding interactions in compound 1 and NCS···H‐N hydrogen‐bonding interactions and NCS—SCN interactions in compound 2 play a significant role in aligning the polymer strands in crystalline solids.