A novel approach to the synthesis of diaza-bridged heterocycle derivatives

A novel synthetic route of diaza-bridged heterocycles based on natural 3,9-diazabicyclo[3.3.1]non-6-ene scaffold has been accomplished. The synthetic approach consists of a Pictet-Spengler condensation of the l-Dopa-OMe with an appropriate aldehyde, Fmoc-Aa-H, followed by intramolecular lactamization. This approach generated two configurationally distinct products (cis and trans-isomers), increasing the stereochemical diversity of these compounds. The synthesized compounds are potentially useful in the discovery of novel pharmacologically active compounds.     

Mapping protein pockets through their potential small-molecule binding volumes: QSCD applied to biological protein structures

Previously we demonstrated a method, Quantized Surface Complementarity Diversity (QSCD), of defining molecular diversity by measuring shape and functional complementarity of molecules to a basis set of theoretical target surfaces [Wintner E.A. and Moallemi C.C., J. Med. Chem., 43 (2000) 1993]. In this paper we demonstrate a method of mapping actual protein pockets to the same basis set of theoretical target surfaces, thereby allowing categorization of protein pockets by their properties of shape and functionality. The key step in the mapping is a `dissection' algorithm that breaks any protein pocket into a set of potential small molecule binding volumes. It is these binding volumes that are mapped to the basis set of theoretical target surfaces, thus measuring a protein pocket not as a single surface but as a collection of molecular recognition environments.     

Skeletal and appendage diversity as design elements in the synthesis of a discovery library of nonaromatic polycyclic 5-iminooxazolidin-2-ones, hydantoins, and acylureas

Amino-acid derived cross-conjugated trienes were used as a starting point for the synthesis of a discovery library of over 200 polycyclic 5-iminooxazolidin-2-ones, hydantoins, and acylureas. The main feature of this library synthesis is a triple branching strategy, which provides efficient access to five skeletally diverse scaffolds. In addition, four sets of building blocks were applied in both a front end and a back end diversification strategy. Multiple fused rings were obtained by cyclization of diamides with phosgene and stereoselective Diels-Alder reactions with maleimides. The 5-iminooxazolidin-2-one scaffold was rearranged into the isomeric hydantoin scaffold through a sequence of ring-opening and ring-closing reactions.     

A Model of 60 GHz Indoor Radio Channel

A novel model of millimeter-wave (MMW) indoor radio channel is presented in this paper. The model is related the random properties of the MMW radio channel to the underlying geometry of the environment. The geometric simplicity of the MMW channel is allowed examining fundamental deterministic properties of the wave propagation behavior in environments of predefined randomness. The dimensions and properties of environments are described by various probability distributions. Stochastic influence on the radio channel is studied for the down-link of a wireless local area network at 60 GHz. Other related factors, such as amplitudes of path lengths, angles of departure, and amplitudes, as well as spatial power densities, average power of the direct paths are investigated.     

东疆部分地区寄生蜂资源的初步调查

本文通过对新疆东部部分地区寄生蜂资源进行初步调查,并应用生物多样性主要特性指数的分析方法,对不同地区采集到的5 705头标本进行多样性分析。东疆的寄生蜂资源主要集中在以姬小蜂科Eu loph idae、金小蜂科P terom a lidae、环腹瘿蜂科F ig itidae、茧蜂科B racon idae、蚜茧蜂科A ph id iidae、姬蜂科Ichneum on idae等为主的27科。结果表明:巴里坤山前草地的寄生蜂多样性指数最高,而在巴里坤农田的寄生蜂多样性指数最低;木垒山地草原的寄生蜂丰富度指数最高,而多样性指数则比较低;各地物种优势度相差不大。     

Diversity‐oriented synthesis

Diversity‐oriented synthesis (DOS), which describes the synthesis of structurally diverse collections of small molecules, was developed, in part, to address combinatorial chemistry's shortfalls. In this paper, we hope to give an indication of what can be achieved using the DOS approach to library generation. We describe some of the most successful strategies utilized in DOS, with special focus on our own area of interest; DOS from simple, pluripotent starting materials. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 129–142; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20144     

1H NMR spectroscopy with internal and external standards for the quantification of libraries

A convenient and easy method based on 1H NMR spectroscopy with both external and internal standards is described for the quantification of members of libraries.     

Comments on the design of chemical libraries for screening

Different representations of molecules, based ondistinct sets of properties can yield differentperspectives of the issues involved in library design.In particular, different chemical representations cangive rise to very different estimates of requiredlibrary sizes. We provide a preliminary mathematicalframework that examines the size of libraries requiredto adequately sample the spaces corresponding to somecommonly used property sets. Introduction ofconformational flexibility is also discussed as ameans of increasing coverage of chemical libraries,while at the same time considering the thermodynamicconsequences of flexibility upon detectable activity.Our theoretical analysis reveals that the propertyspaces currently in use are extremely large andunlikely to provide adequate discrimination amongcompounds.     

渥拉斯顿棱镜在不同方式组合下的光路特性分析

分析了具有相同结构角的两个渥拉斯顿棱镜在不同方式组合下的光路特性。给出了分束角与结构角的关系表达式,同时也给出了分束角与结构角的关系曲线。使用He Ne激光器(波长λ=633nm)对两个结构角S=27°的渥拉斯顿棱镜在四种不同组合方式下的光路进行了测试。结果表明,测试结果与理论计算完全相符。