Streamlined construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation in solution and on DNA

A highly efficient and versatile method for construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation of alkyl and aryl thiols with aryl iodides under mild conditions is developed. The method exhibits a broad substrate scope for thiols, aryl iodides and amino acid units. Peptide macrocycles of a wide range of size and composition can be readily assembled in high yield from various easily accessible building blocks. This method has been successfully employed to prepare an 8-million-membered tetrameric cyclic peptide DNA-encoded library (DEL). Preliminary screening of the DEL library against protein p300 identified compounds with single digit micromolar inhibition activity.

A highly efficient and versatile method for construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation of alkyl and aryl thiols with aryl iodides under mild conditions is developed.     

Synthesis and stereochemical assignment of 7-arylidene and 7-heteroarylidene morphinan-6-ones

A number of (E)-7-arylidenenaltrexones were synthesized by azeotropic distillation of water from a benzene solution of naltrexone and an aromatic aldehyde (benzaldehyde, 4-chloro- and 4-fluorobenzaldehyde, 3-and 4-pyridinecarboxaldehyde and 1-methyl-2-imidazolecarboxaldehyde) using piperidine as a catalyst. In addition, (E)-7-benzylidenenaloxone was prepared by the previously published Claisen-Schmidt condensation using sodium hydroxide in methanol. The stereochemistry of these arylidene derivatives 3–9 was determined to be (E) by means of nuclear Overhauser enhancement experiments. The ¹³C nmr spectra of (E)- 3–9 are recorded in deuteriochloroform and those of the hydrochlorides in deuteriodimethyl sulfoxide.     

呋喃丹的极谱法测定研究及应用

用循环伏安法(CV)、线性扫描伏安法(LSV)对呋喃丹的极谱伏安行为及其测定进行了研究。在0.2mol/L NH3-NH4Cl底液中(pH 8.8),对其进行扫描,发现于-1.21V(vs.SCE)处产生一灵敏的还原峰,其峰电流与呋喃丹的浓度在5.0×10-6-1.0×10-mol/L范围内呈良好的线性关系(r=0.9995)。对5.0×10-5mol/L呋喃丹溶液进行6次平行实验,RSD为0.2％。实验结果表明,呋喃丹在极谱电极上有吸附性质。同时对电极反应机理进行了研究。该方法对微生物降解呋喃丹进行监测取得满意的结果,96 h内呋喃丹的降解率为98％。     

纤维素基磁性聚偕氨肟树脂吸附Mn（Ⅶ）

用酸处理的纤维素基磁性聚偕氨肟树脂（AMAO）在溶液中吸附KMnO4，发生氧化还原反应的几率在2％以下；用碱处理的树脂（BMAO）作吸附剂，KMnO4还原为Mn（OH）4的比例剧增，达到或超过10％，并且与溶液的pH有关。但是，Mn（Ⅶ）被还原为Mn（Ⅳ）的量基本上不受KMnO4起始浓度、吸附剂添加量和吸附时间变化的影响。BMAO树脂吸附KMnO4的量是树脂偕氨肟基含量的5倍以上。超当量吸附现象反映了物理吸附的本质。     

吡咯-IR法测定铝化β沸石的碱性

The basicities of aluminated zeolites βhave been investigated by FTIR spectra of chemisorbed pyrrole. The NH-stretching frequency of pyrrole adsorbed on the samples shifts towards lower wavenumber as the St/Al ratio is decreased and correlates well with the negative charge on the framework oxygen calculated from the Sanderson electronegativity equalization principle, revealing zeolite β to possess a stronger overall basicity after alumination and, therefore, the alumination to be an effective method to improve the basicity. It is also found that the heterogeneity of basic strength occurs and some stronger basic sites appear after alumination.     

Multi-dimple phenomena in TEHL point contacts

Theoretical analysis and experimental measurement of the multiple dimples in thermal elastohydrodynamic lubrication (TEHL) point contacts have been carried out. Good agreement is found between the theoretical and experimental results. A thermal multi-spike theory is proposed to explain the multi-dimple phenomena.     

二氧化碳—环氧丙烷—甲苯二异氰酸酯的三元共聚

二氧化碳和环氧丙烷(PO)在阴离子配位催化剂,如二乙基锌和等摩尔的水作用下,可接式(1)发生共聚。但产物聚丙撑碳酸酯(PPC)的热稳定性较差。改进途径之一是在反应中引入甲苯二异氰酸酯(TDI)进行三元共聚。本文报导在双金属阴离子配位催化剂PBM存在下合成一种热稳定性优于PPC的聚碳酸酯聚氨酯(PCPU)的研究结果(式2)。     

硅氧烷乳液聚合的研究——Ⅱ.八甲基环四硅氧烷阳离子乳液聚合机理

根据八甲基环四硅氧烷(D_4)在阳离子乳液聚合过程中,聚合物的分子量及数目的变化等特点,提出并证明了D_4在乳液粒子表面进行聚合的机理的假设。     

纳米分辨率的三维形貌检测仪

从光干涉方式，瞳窗关系和光源带宽等基本关系出发，利用空间不变系统理论解析了相移显微干涉检测系统中衍射效应的影响。为了减小横向分辨率对纵向分辨率的影响，利用相关信息提取或数字滤波的方法，获得了纳米分辨率的三维形貌。