(DPPA). The reactionprocedure is quite simple, occurring by refluxing an equimolecular mixture of a carboxylic acid, DPPA, and triethylamine in the presence of a hydroxyl component. Aromatic, aliphatic, and heterocyclic carboxylic acids underwent rearrangements in satisfactory yields. As this modified Curtins reaction is much simpler and less laborious than the classical Curtius reaction and proceeds
Triiodide-Mediated δ-Amination of Secondary C−H Bonds
作者:Ethan A. Wappes、Stacy C. Fosu、Trevor C. Chopko、David A. Nagib
DOI:10.1002/anie.201604704
日期:2016.8.16
amination of unactivated, secondary C−Hbonds to form a broad range of functionalized pyrrolidines has been developed by a triiodide (I3−)‐mediated strategy. By in situ 1) oxidation of sodium iodide and 2) sequestration of the transiently generated iodine (I2) as I3−, this approach precludes undesired I2‐mediated decomposition which can otherwise limit synthetic utility to only weak C(sp3)−H bonds. The mechanism
Hydrogels that degrade under appropriate conditions of pH and temperature by virtue of crosslinking compounds that cleave through an elimination reaction are described. The hydrogels may be used for delivery of various agents, such as pharmaceuticals.
Agent for Preventing or Ameliorating Hearing Impairment
申请人:Tohoku University
公开号:US20190224165A1
公开(公告)日:2019-07-25
It is to provide an agent for preventing or improving hearing loss, which comprises a low molecular compound which can be produced relatively easily and inexpensively as an active ingredient. One or more compounds selected from the group consisting of compounds represented by the following formulas (I
0
), (II), and (III) and a pharmaceutically acceptable salt of the compounds when R
3
is OH are used as an agent for preventing or improving hearing loss.
β-Alanine-Based Dendritic β-Peptides: Dendrimers Possessing Unusually Strong Binding Ability Towards Protic Solvents and Their Self-Assembly into Nanoscale Aggregates through Hydrogen-Bond Interactions
and amide groups, the dendrimers exhibit an unusuallystrongbinding ability towards protic solvents and behave as H-bond sponges. As a result, the H/D exchange rates of the N-H protons are significantly enhanced in such dendritic structures, as compared to those of nondendritic carbamates and amides. These dendritic peptide dendrimers also exhibit a strong tendency to form nanoscopic aggregates in nonpolar
具有Boc-氨基甲酸酯作为表面官能团,β-丙氨酸作为树状分支,3,5-二氨基苯甲酸作为支化剂,以及1,2-二氨基乙烷作为内芯的一系列聚(β-丙氨酸)树枝状聚合物1-4具有通过溶液相肽偶联方法合成了α-己内酰胺。产物的结构特征和纯度已通过光谱和色谱法充分表征。对树枝状聚合物的1 H NMR研究表明,Boc-氨基甲酸酯表面基团以溶液中的顺式和反式旋转异构体的混合物形式存在,并且树枝状化合物在极性溶剂中采用开放结构。这允许内部核心功能与溶剂分子自由相互作用。由于大量氨基甲酸酯和酰胺基团的协同作用,树枝状聚合物对质子溶剂表现出异常强的结合能力,并表现为氢键海绵。结果,与非树状氨基甲酸酯和酰胺相比,在这种树状结构中NH质子的H / D交换速率显着提高。这些树突肽树状聚合物还表现出很强的趋势,可通过分子间的氢键相互作用在非极性或极性非质子溶剂中形成纳米聚集体。