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861.
Ryo Hirata Ayame Torii Kenichi Kawano Shiroh Futaki Ayumi Imayoshi Kazunori Tsubaki 《Tetrahedron》2018,74(27):3608-3615
Fluorescent dyes possessing a variety of arylacetylenes at the 9-position of a xanthene skeleton were synthesized and their optical properties were investigated. The π system effectively expanded over the xanthene skeleton and the aryl group through the triple bond. Starting from the emission wavelength (λem) of 9-methyl xanthene 20 in basic DMSO solution at 536?nm, the emission wavelengths gradually shifted to the red region for methylacetylene 17 (λem?=?600?nm), phenylacetylene 5 (λem?=?636?nm), and p-CF3-phenylacetylene 11 (λem?=?660?nm). On the basis of these data, we estimated the substituent effects for the red shift on the emission wavelength and rationally explained the results by DFT calculations. Furthermore, potential applicability of these fluorescent dyes to cell staining was exemplified. 相似文献
862.
An alternative synthetic route to 1,4,5-trisubstituted imidazoles from α-imino ketone, which can be prepared from imidoyl chlorides and aromatic aldehydes via N-heterocycle carbene-catalyzed aroylation was developed. This methodology consists of simple transformations, allowing a rapid access to imidazole derivatives with various aryl substituents at the desired positions. 相似文献
863.
Fluctuating Carbonaceous Networks with a Persistent Molecular Shape: A Saddle‐Shaped Geodesic Framework of 1,3,5‐Trisubstituted Benzene (Phenine)
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Dr. Koki Ikemoto Jennie Lin Ryo Kobayashi Dr. Sota Sato Prof. Dr. Hiroyuki Isobe 《Angewandte Chemie (International ed. in English)》2018,57(28):8555-8559
A saddle‐shaped macromolecule has been synthesized. The molecule was designed as a geodesic saddle with 1,3,5‐trisubstituted benzene (named phenine) as the fundamental unit. The phenines were woven into a polygonal framework that was composed of 168 sp2‐hybridized carbon atoms. The saddle‐shaped structure with unique symmetry showed atypical conformational changes. The biaryl linkages in this molecule had a small energy barrier for rotation, and these structural fluctuations resulted in seven 1H NMR resonances representing 84 aromatic hydrogen atoms. Nevertheless, the overall saddle shape of the molecule was persistent, and the “up” and “down” orientations of phenine moieties circulated to give average 1H resonances. The structural characteristics of this molecule, including the anomalous entropy‐driven dimerization, may deepen our understanding of defect‐rich graphitic sheets. 相似文献
864.
Metal‐ and Oxidant‐Free Alkenyl C−H/Aromatic C−H Cross‐Coupling Using Electrochemically Generated Iodosulfonium Ions
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Dr. Ryutaro Hayashi Dr. Akihiro Shimizu Jonathan A. Davies Yu Ishizaki Prof. Dr. Chris Willis Prof. Dr. Jun‐ichi Yoshida 《Angewandte Chemie (International ed. in English)》2018,57(39):12891-12895
A three‐step transformation consisting of 1) addition of electrochemically generated iodosulfonium ions to vinylarenes to give (1‐aryl‐2‐iodoethoxy)sulfonium ions, 2) nucleophilic substitution by subsequently added aromatic compounds to give 1,1‐diaryl‐2‐iodoethane, and 3) elimination of HI with a base to give 1,1‐diarylethenes was developed. The transformation serves as a powerful metal‐ and chemical‐oxidant‐free method for alkenyl C?H/aromatic C?H cross‐coupling. 相似文献
865.
Inside Back Cover: Giant Hysteretic Single‐Molecule Electric Polarisation Switching above Room Temperature (Angew. Chem. Int. Ed. 41/2018)
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866.
Dr. Heejin Kim Yuya Yonekura Prof. Dr. Jun‐ichi Yoshida 《Angewandte Chemie (International ed. in English)》2018,57(15):4063-4066
Reported is the electrophilic amination of functional organolithium intermediates with well‐designed aminating reagents under mild reaction conditions using flow microreactors. The aminating reagents were optimized to achieve efficient C?N bond formation without using any catalyst. The electrophilic amination reactions of functionalized aryllithiums were successfully conducted under mild reaction conditions, within 1 minute, by using flow microreactors. The aminating reagent was also prepared by the flow method. Based on stopped‐flow NMR analysis, the reaction time for the preparation of the aminating reagent was quickly optimized without the necessity of work‐up. Integrated one‐flow synthesis consisting of the generation of an aryllithium, the preparation of an aminating reagent, and their combined reaction was successfully achieved to give the desired amine within 5 minutes of total reaction time. 相似文献
867.
Dr. Masahito Yoshida Dr. Koya Saito Dr. Hikaru Kato Prof. Dr. Sachiko Tsukamoto Prof. Dr. Takayuki Doi 《Angewandte Chemie (International ed. in English)》2018,57(18):5147-5150
The total synthesis of siladenoserinol A, an inhibitor of the p53–Hdm2 interaction, has been achieved. AuCl3‐catalyzed hydroalkoxylation of an alkynoate derivative smoothly and regioselectively proceeded to afford a bicycloketal in excellent yield. A glycerophosphocholine moiety was successfully introduced through the Horner–Wadsworth–Emmons reaction using an originally developed phosphonoacetate derivative. Finally, removal of the acid‐labile protecting groups, followed by regioselective sulfamate formation of the serinol moiety afforded the desired siladenoserinol A, and benzoyl and desulfamated analogues were also successfully synthesized. Biological evaluation showed that the sulfamate is essential for biological activity, and modification of the acyl group on the bicycloketal can improve the inhibitory activity against the p53–Hdm2 interaction. 相似文献
868.
Cover Picture: Catalyst‐Enabled Site‐Divergent Stereoselective Michael Reactions: Overriding Intrinsic Reactivity of Enynyl Carbonyl Acceptors (Angew. Chem. Int. Ed. 17/2018)
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869.
One‐pot Annulation for Biaryl‐fused Monocarba‐closo‐dodecaborate through Aromatic B−H Bond Disconnection
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Gaku Akimoto Mai Otsuka Dr. Kazunori Miyamoto Dr. Atsuya Muranaka Dr. Daisuke Hashizume Dr. Ryo Takita Prof. Dr. Masanobu Uchiyama 《化学:亚洲杂志》2018,13(8):913-917
We have developed a one‐pot annulation reaction of monocarba‐closo‐dodecaborate with cyclic diaryliodonium salts to afford biaryl‐fused derivatives. Aryl functionalities are introduced at both the 1‐carbon and unreactive ortho‐boron vertices of the “σ‐aromatic” carborane cage without the need for pre‐functionalization. DFT calculations revealed that the palladium‐catalyzed C?B bond‐formation step in this process proceeds through a concerted metalation–deprotonation (CMD)‐type pathway for the B?H bond disconnection on the aromatic cage, though such bonds are generally regarded as hydridic. 相似文献
870.
Matsuta K. Minamisono T. Tanigaki M. Fukuda M. Nojiri Y. Mihara M. Onishi T. Yamaguchi T. Harada A. Sasaki M. Miyake T. Minamisono K. Fukao T. Sato K. Matsumoto Y. Ohtsubo T. Fukuda S. Momota S. Yoshida K. Ozawa A. Kobayashi T. Tanihata I. Alonso J. R. Krebs G. F. Symons T. J. M. 《Hyperfine Interactions》1996,97(1):519-526
The magnetic moments of the proton drip-line nuclei13O(I
= 3/2–,T
1/2 = 8.6 ms) and 9C(I
= 3/2–,T
1/2 = 126 ms) have been determined for the first time through the combined techniques of polarized radioactive nuclear beams and-NMR detection. The observed magnetic moments are ¦(13O)¦ = 1.3891 ±0.0003
N and ¦(9C)¦ = 1.3914 ±0.0005
N. Spin expectation values are deduced to be 0.76 and 1.44 for13O and9C, respectively. While the of13O is consistent with the systematics from isospinT= 1/2 mirror pairs, the of9C is unusually large, even far larger than the single particle value, = 1. 相似文献