Monoprotected <scp>l</scp>
-Amino Acid (<scp>l</scp>
-MPAA), Accelerated Bromination, Chlorination, and Iodination of C(sp<sup>2</sup>
)−H Bonds by Iridium(III) Catalysis
作者:Subban Kathiravan、Ian A. Nicholls
DOI:10.1002/chem.201700280
日期:2017.5.23
Halogenated arenes are important structural motifs commonly found in biologically active molecules and used for a variety of transformations in organic synthesis. Herein, we report the mono-protected L-amino acid (L-MPAA) accelerated iridium(III) catalyzed halogenation of (hetero)anilides at room temperature. This reaction constitutes the first example of an iridium(III)/L-MPAA catalyzed general halogenation
Structure–Activity Relationship Study of Heterocyclic Phenylethenyl and Pyridinylethenyl Derivatives as Tau-Imaging Agents That Selectively Detect Neurofibrillary Tangles in Alzheimer’s Disease Brains
In order to explore novel tau-imaging agents that can selectively detect neurofibrillary tangles in Alzheimer's disease (AD) brains, we designed and synthesized a series of heterocyclic phenylethenyl and (3-pyridinyl)ethenyl derivatives with or without a dimethyl amino group. In in vitro autoradiography using AD brain sections, all radioiodinated ligands with a dimethyl amino group bound to A beta deposits in the sections. In contrast, the ligands without a dimethyl amino group showed different patterns of radioactivity accumulation in the sections depending on the kind of heterocycle contained in their molecules. Particularly, a phenylethenyl benzimidazole derivative ([I-125]64) showed marked radioactivity accumulation in the temporal lobe which corresponded with the distribution of tau deposits. [I-125]64 also showed the most favorable pharmacokinetics in normal mouse brains (3.69 and 0.06% ID/g at 2 and 60 min postinjection, respectively) among all ligands in this study. Taken together, these results suggest that [I-123]64 may be a new candidate tau-imaging agent.
Catalysis and Regioselectivity of the Aqueous Heck Reaction by Pd(0) Nanoparticles under Ultrasonic Irradiation
An aqueous Heck reaction carried out under ultrasonic irradiation at the ambient temperature (25 degrees C) has been shown in this study to afford high yields of corresponding products. It was found that as a catalyst for the reaction palladium forms nanoparticles in-situ, characterized by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analyses, and can be recycled. Furthermore, the Heck reaction under such mild and environmentally friendly conditions offers excellent regioselectivity of para-over ortho-substitution in phenyl iodides especially with electron-donating groups.
Michael; Norton, Chemische Berichte, 1878, vol. 11, p. 109