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Angewandte Chemie

Tia E Keyes, Christopher Burke, Aisling Byrne
Mitochondrial DNA (mtDNA) plays a crucial but incompletely understood role in cellular biochemistry and etiology of numerous disease states. Thus, there is an urgent need for targeted probes that can dynamically respond to changes to mtDNA such as copy number in live cells, but it is difficult to permeate the mitochondrial membrane of the living cell. Herein, we present a ruthenium(II) light-switching probe targeted by peptide vectorization selectively to mitochondrial nucleoids. Evidence for DNA binding by the probe in live cells is derived from confocal fluorescence microscopy, resonance Raman and luminescence lifetime imaging...
July 17, 2018: Angewandte Chemie
Lei Liu, Honghao Guan, Shutao Sun, Ying Mao, Lei Chen, Ran Lu, Jiancheng Huang
An alkoxyl radical-guided strategy for site-selective functionalization of unactivated methylene and methine C-H bonds enabled by an Fe(II)-catalyzed orchestrated redox process is described. The mild, expeditious, and modular protocol allows for efficient remote aliphatic fluorination, chlorination, amination, and alkynylation of structurally and electronically varied primary, secondary, and tertiary hydroperoxides with excellent functional group tolerance. The application in one-pot 1,4-hydroxyl-functionalization of non-oxygenated alkane substrates initiated by aerobic C-H oxygenation is also demonstrated...
July 17, 2018: Angewandte Chemie
Ilana B Stone, Janis Jermaks, Samantha N MacMillan, Tristan Hayes Lambert
An organocatalytic oxidation platform that capitalizes on the capacity of hydrazines to undergo rapid autoxidation to diazenes is described. Commercially available benzo[c]cinnoline is shown to catalyze the oxidation of alkyl halides to aldehydes via a novel mechanistic paradigm involving nucleophilic attack, prototropic shift, and hydrolysis. The hydrolysis and reoxidation events occur readily with only adventitious oxygen and water. A survey of the scope of viable substrates is shown along with mechanistic and computational studies that give insight into this mode of catalysis...
July 17, 2018: Angewandte Chemie
Xiaopin Duan, Christina Chan, Wenbin Lin
Cancer immunotherapies by training or stimulating the inherent immunological systems to recognize, attack, and eradicate tumor cells with minimal damage to healthy cells have demonstrated promising clinical responses in recent years. However, most of these immunotherapeutic strategies only benefit a small subset of patients and cause systemic autoimmune side effects in some patients. Immunogenic cell death (ICD)-inducing modalities not only directly kill cancer cells, but also induce antitumor immune responses against a broad spectrum of solid tumors...
July 17, 2018: Angewandte Chemie
Wen Yang, Dengke Ma, Yu Zhou, Xiuqin Dong, Zhenyang Lin, Jianwei Sun
Described here is the first NHC-catalyzed γ-trifluoromethylation of vinylogous enolates. The reaction features high regioselectivity and efficiency. Control experiments and DFT calculations provided important insights into the reaction mechanism.
July 17, 2018: Angewandte Chemie
Qun Cao, Joseph L Howard, Emilie Wheatley, Duncan L Browne
A form independent activation of zinc, concomitant generation of organozinc species and engagement in a Negishi cross-coupling reaction via mechanochemical methods is reported. The reported method exhibits a broad substrate scope for both Csp3-Csp2 and Csp2-Csp2 couplings and is tolerant to many important functional groups. The method may offer broad reaching opportunities for the in situ generation and use of organometallic compounds from base metals and their subsequent engagement in synthetic reactions via mechanochemical methods...
July 17, 2018: Angewandte Chemie
Malek Y S Ibrahim, Scott E Denmark
A novel Pd/Rh dual-metallic cooperative catalytic process has been developed to effect the reductive carbonylation of aryl halides in moderate to good yield. In this reaction, water is the hydride source, and CO serves both as the carbonyl source and the terminal reductant through the water-gas shift reaction. The catalytic generation of the Rh hydride allows for the selective formation of highly hindered aryl aldehydes that are inaccessible through previously reported reductive carbonylation protocols. Moreover, aldehydes with deuterated formyl groups can be efficiently and selectively synthesized using D2 O as a cost-effective deuterium source without the need for presynthesizing the aldehyde...
July 17, 2018: Angewandte Chemie
Pierre Audebert, Fabien Miomandre, Yangyang Qu, François-Xavier Sauvage, Gilles Clavier
A facile, efficient and metal-free synthetic approach to 3-monosubstituted unsymmetrical 1,2,4,5-tetrazines is presented. Dichloromethane (DCM) is for the first time recognized as a novel reagent in the synthetic chemistry of tetrazines. Eleven 3-aryl/alkyl 1,2,4,5-tetrazines were prepared in excellent yields (up to 75%) through this novel approach. The mechanism of this new reaction, including the role of DCM in the tetrazine ring formation, has been investigated by DCM13C labeling, and is also presented and discussed as well as the photophysical and electrochemical properties...
July 17, 2018: Angewandte Chemie
Pedro J Pérez, Andrea Olmos, Riccardo Gava, Barbara Noverges, Delia Belleza, Kane Jacob, Maria Besora, W M Chamil Sameera, Michel Etienne, Feliu Maseras, Gregorio Asensio, Ana Caballero
We report the quantitative measurement of the relative reactivity of a series of C-H bonds of gaseous or liquid CnH2n+2 alkanes (n = 1-8, 29 different C-H bonds), toward in situ generated electrophiles (copper-, silver- or rhodium-carbenes), with methane as the reference. This strategy surpasses the drawback of previous model reactions of alkanes with strong electrophiles suffering from C-C cleavage processes, which precluded direct comparison of relative reactivity of alkane C-H bonds.
July 17, 2018: Angewandte Chemie
Yannan Yang, Jie Tang, Prasanna Lakshmi Abbaraju, Manasi Jambhrunkar, Hao Song, Min Zhang, Chang Lei, Jianye Fu, Zhengying Gu, Yang Liu, Chengzhong Yu
Immuno-suppressive tumours generally exhibit poor response to immune checkpoint blockade based cancer immunotherapy. In the present work, we report that rationally designed hybrid nanoreactors have integrated functions as Fenton catalysts and glutathione depletion agents for amplifying the immunogenic cell death and activating immune cells. A simple physical mixture of nanoreactors and chemodrugs in combination with immune checkpoint blockades show synergistically and concurrently enhanced chemo-immunotherapy efficacy, inhibiting the growth of both treated primary immuno-suppressive tumours and untreated distant tumours...
July 16, 2018: Angewandte Chemie
Thomas Scattolin, Erdem Senol, Guoyin Yin, Qianqian Guo, Franziska Schoenebeck
This report widens the repertoire of emerging Pd(I) catalysis to carbon-heteroatom, i.e. C-S bond formation. While Pd(0) catalyzed protocols may suffer from the formation of poisonous sulfide bound off-cycle intermediates and lack of selectivity, the mechanistically diverse Pd(I) catalysis concept circumvents these challenges and allows for C-S bond formation (S-Aryl and S-Alkyl) of a wide range of aryl halides. Site-selective thiolations of C-Br sites in the presence of C-Cl and C-OTf were achieved in a general and a priori predictable fashion...
July 16, 2018: Angewandte Chemie
Youske Akae, Hiromitsu Sogawa, Toshikazu Takata
The challenging synthesis of an alpha-cyclodextrin (CD)-based macromolecular rotaxane with definite structure was fulfilled using a size-complementary protocol. A new peracetylated (PAc) alpha-CD-based size-complementary [3]rotaxane was prepared and its thermal dissociation kinetics was studied. The deslippage mechanism was found to be different from that of the native alpha-CD-based system. PAcalpha-CD-based size-complementary [3]rotaxanes were employed as initiators for a ring-opening polymerization of epsilon-caprolactone to obtain the macromolecular [3]rotaxanes...
July 16, 2018: Angewandte Chemie
Kevin Schwarz, Chao Yang, James Fyfe, Thomas Neil Snaddon
The first asymmetric cooperative Lewis base/Pd benzylic alkylation of acyclic esters is reported. This reaction proceeds via stereo-defined C1-ammonium enolate nucleophiles and critical to its success was the identification of benzylic phosphate electrophiles, which were uniquely reactive. Alkylated products are obtained with very high levels of enantioselectivity and this method has been applied toward the synthesis of the thrombin inhibitor DX-9065a.
July 16, 2018: Angewandte Chemie
Vanessa Béland, Zhiqiang Wang, Tsun-Kong Sham, Paul J Ragogna
The synthesis of phosphane-ene photopolymer networks (A), where the networks are composed of crosslinked tertiary alkyl phosphines are reported. Taking advantage of the rich coordination chemistry of alkyl phosphines, we were able to generate stibino-phosphonium (B) and stibino-bis(phosphonium) (C) functionalized polymer networks. Small molecule stibino-phosphonium and stibino-bis(phosphonium) compounds are well characterized in the literature and were used as models for spectroscopic comparison to the macromolecular analogues by NMR and XANES spectroscopies...
July 16, 2018: Angewandte Chemie
Long Huang, Magnus Rueping
An efficient protocol for the direct allylic C(sp3 )-H bond activation of unactivated tri- and tetrasubstituted alkenes and their functionalization with aryl- and vinylbromides by nickel and visible-light photocatalysis has been developed. The method allows C(sp2 )-C(sp3 ) formation under mild reaction conditions with good functional-group tolerance and excellent regioselectivity.
July 16, 2018: Angewandte Chemie
Erwann Le Coz, Vincent Dorcet, Thierry Roisnel, Sven Tobisch, Jean-Francois Carpentier, Yann Sarazin
The first soluble barium boryloxides [Ba]-OB{CH(SiMe3)2} are presented. These mono- or dinuclear complexes feature low coordination numbers, as low as two for [Ba(OB{CH(SiMe3)2}2)2], which is further stabilized by intra- and intermolecular Ba···H3C agostic interactions. Ba-boryloxides and the parent [Ba{N(SiMe3)2}2.(thf)2] catalyze the dehydrocoupling of borinic acids with hydrosilanes, providing borasiloxanes under mild conditions.
July 16, 2018: Angewandte Chemie
Long Zhang, Chunming Liu, Lingrui Wang, Cailong Liu, Kai Wang, Bo Zou
Low-toxicity, air-stable bismuth-based perovskite materials have emerged as attractive substitutes for lead halide perovskites in photovoltaic and optoelectronic devices. Here, we report the structural, optical and electrical property changes of zero-dimensional lead-free halide perovskite Cs3Bi2I9 resulting from lattice compression. A remarkable emission enhancement under mild pressure should be attributed to the increase in exciton binding energy. Unprecedented band gap narrowing originated from Bi-I bond contraction, and the decrease in bridging Bi-I-Bi angle enhances metal halide orbital overlap, thereby successfully breaking through the Shockley-Queisser limit under relatively low pressure...
July 16, 2018: Angewandte Chemie
Zhikun Wu
The emergence of thiolated metal nanoclusters provides excellent opportunities to identify significant and unprecedented phenomena because they are at quantum sizes and can be characterized with X-ray crystallography. Recently silver nanoclusters have received extensive interests due to their merits such as low cost and rich properties. Herein, a novel thiolated silver nanocluster [Ag46S7(SPhMe2)24]NO3 (Ag46 for short) with a face-centered cubic (fcc) structure was successfully synthesized and structurally resolved by X-ray analysis...
July 16, 2018: Angewandte Chemie
Zhaojun Liu, Jing Qi, Moxuan Liu, Shumeng Zhang, Qikui Fan, Hongpo Liu, Kai Liu, Haoquan Zheng, Yadong Yin, Chuanbo Gao
Although aqueous synthesis of nanocrystals is advantageous in terms of the cost, convenience, environmental friendliness, and surface cleanness of the product, nanocrystals of Pt and non-noble metal alloys are difficult to be obtained with controlled morphology and composition from this synthesis due to a huge gap between the reduction potentials of respective metal salts. Here, we report that this huge gap could be remedied by introducing a sulfite into the aqueous synthesis, which is believed to resemble an electroless plating mechanism, giving rise to a colloid of Pt-M (M = Ni, Co, Fe) alloy nanowires with an ultrasmall thickness (~ 2...
July 16, 2018: Angewandte Chemie
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