New Mesogenic Compounds Exhibiting a Thermotropic Optically Isotropic Phase
摘要:
The only two series of carboxylic acids, 3-nitro- or 3-cyano-4-alkoxybiphenyl-4-carboxylic acid, are known to exhibit the optically isotropic phase (SID). Now we synthesised 4-(branched alkoxy)-anilinebenzylidene-4'-carboxylic acid series, all being racemic, and investigated their mesophase properties by means of DSC, optical microscopy and X-ray measurement. A, a result, some branched azomethine derivatives were found to form a SD phase. We also synthesised cinnamic acid derivatives with branched alkoxy tail that were turned out to exhibit either SD phase or hexagonal columnar phase. We tried biphenyl or azobenzene core analogues which were found to produce a highly ordered smectic phase or no mesophase, respectively. At this stage, we suppose it plays an important role that the branch is introduced into the terminal chain and a certain dipole moment is located within the mesogenic core. These factors may allow the peculiar molecular packing that causes an optically isotropic property.
A general N-alkylation platform via copper metallaphotoredox and silyl radical activation of alkyl halides
作者:Nathan W. Dow、Albert Cabré、David W.C. MacMillan
DOI:10.1016/j.chempr.2021.05.005
日期:2021.7
The catalytic union of amides, sulfonamides, anilines, imines, or N-heterocycles with a broad spectrum of electronically and sterically diverse alkyl bromides has been achieved via a visible-light-induced metallaphotoredox platform. The use of a halogen abstraction-radical capture (HARC) mechanism allows for room temperature coupling of C(sp3)-bromides using simple Cu(II) salts, effectively bypassing
通过可见光诱导的金属光氧化还原平台实现了酰胺、磺胺、苯胺、亚胺或N-杂环与广谱电子和空间多样化烷基溴的催化结合。卤素提取-自由基捕获 (HARC) 机制的使用允许使用简单的 Cu(II) 盐在室温下耦合 C( sp 3 )-溴化物,有效绕过通常与热诱导 S N 2 或 S相关的过高障碍N 1 N-烷基化。这种区域和化学选择性方案与 >10 类药物相关的N兼容- 亲核试剂,包括已建立的药剂,以及结构多样的伯、仲和叔烷基溴。此外,通过将N-亲核试剂与环丙基溴和未活化的烷基氯(与亲核取代途径不相容的底物)结合,突出了 HARC 方法与传统惰性偶联伙伴结合的能力。初步的机械实验验证了该平台的双重催化、开壳性质,这使得在传统的基于卤化物的N-烷基化系统中无法实现的反应性成为可能。
FLUORENE-TYPE COMPOUND, PHOTOPOLYMERIZATION INITIATOR COMPRISING SAID FLUORENE-TYPE COMPOUND, AND PHOTOSENSITIVE COMPOSITION CONTAINING SAID PHOTOPOLYMERIZATION INITIATOR
申请人:Daito Chemix Corporation
公开号:US20150259321A1
公开(公告)日:2015-09-17
According to an embodiment of the present invention, there is provided a novel fluorene-based compound and a photopolymerization initiator using the fluorene-based compound. The fluorene-based compound according to an embodiment of the present invention is represented by the general formula (1). A photopolymerization initiator having additionally high sensitivity can be provided by using the fluorene-based compound. In addition, a photopolymerization initiator that can impart additionally excellent characteristics can be provided by appropriately selecting, for example, a substituent.
3-methyl-2-oxobutanoate hydroxymethyltransferase from E. coli (KPHMT) and variants thereof. The 3,3,3-trisubstituted 2-oxoacids thus produced were converted into 2-oxolactones and 3-hydroxy acids and directly to ulosonic acid derivatives, all bearing gem-dialkyl, gem-cycloalkyl, and spirocyclic quaternary centers. In addition, some of these reactions use a single enantiomer from racemic nucleophiles to afford
Direct Bromination and Iodination of Non-Activated Alkanes by Hypohalite Reagents
作者:Thomas Wirth、Raúl Montoro
DOI:10.1055/s-2005-865322
日期:——
The direct functionalisation of alkanes through bromination and iodination has been successfully achieved. The combination of stoichiometric mixtures of elemental halogen and sodium alkoxides leads to the formation of alkyl hypobromites and hypoiodites as reagents. The halogenation occurs without external photostimulation under thermal reaction conditions.
Reductive coupling of benzyl oxalates with highly functionalized alkyl bromides by nickel catalysis
作者:Xiao-Biao Yan、Chun-Ling Li、Wen-Jie Jin、Peng Guo、Xing-Zhong Shu
DOI:10.1039/c8sc00609a
日期:——
Coupling reactions involving non-sulfonated C–O electrophiles provide a promising method for forming C–C bonds, but the incorporation of functionalized or secondary alkyl groups remains a challenge due to the requirement for well-defined alkylmetal species. In this study, we report a reductive nickel-catalyzed cross-coupling of benzyl oxalates with alkyl bromides, using oxalate as a new leaving group