Read by QxMD icon Read

Organic & Biomolecular Chemistry

Navdeep Kaur, Fan Wu, Nur-E Alom, Jeewani P Ariyarathna, Shannon J Saluga, Wei Li
Saturated heterocycles are important structural motifs in a range of pharmaceuticals and agrochemicals. As a result of their importance, syntheses of these molecules have been extensively investigated. Despite the progress in this area, the most adopted strategies are still often characterized with inefficiency or relying on functionalizations with specialized precursors and pre-existing cores. This review highlights a dynamic synthetic strategy for the direct synthesis of saturated heterocycles from intermolecular alkene difunctionalizations...
November 19, 2018: Organic & Biomolecular Chemistry
Cecilia I Attorresi, Evelyn L Bonifazi, Javier A Ramírez, Gabriel F Gola
A pseudo-five-multicomponent reaction involving an isocyanide, a primary amine, two molecules of formaldehyde and water is reported, which gives N,N'-substituted 4-imidazolidinones when trifluoroethanol is used as the solvent. The reaction proceeds with good yields and with a wide variety of amines and isocyanides, providing an efficient new entry to these heterocycles. A preliminary study of the reaction mechanism suggests that trifluoroethanol, although acting as the solvent, is directly involved as a reagent in the reaction pathway...
November 19, 2018: Organic & Biomolecular Chemistry
Qiang Fu, Rui Wang, Fushun Liang, Wei Guan
Perfluoroalkyl-containing aza-tricycles have been prepared in one synthetic operation via an ambient light-promoted three-component reaction of β-oxo esters, perfluoroalkyl iodide and DBU. Intramolecular C-FO and double C-HF weak interactions and intermolecular C-HO and C-Hπ hydrogen bondings were observed partly due to the incorporation of the perfluoroalkyl group. The perfluoroalkylated non-planar aza-tricycles exhibit interesting room-temperature AIE fluorescence and acid-induced fluorescence enhancement characters...
November 19, 2018: Organic & Biomolecular Chemistry
Norihiko Takeda, Mizuki Furuishi, Yuri Nishijima, Erika Futaki, Masafumi Ueda, Tetsuro Shinada, Okiko Miyata
An effective asymmetric α-phenylation of methyl ketones with triphenylaluminium in the presence of (+)-benzopyranoisoxazolidine has been developed. The reaction proceeds via the in situ formation of a chiral N-alkoxyenamine and the subsequent diastereoselective nucleophilic phenylation to provide α-phenylated products in moderate to good yields, with high enantioselectivities.
November 19, 2018: Organic & Biomolecular Chemistry
Mojmír Suchý, Caitlin Lazurko, Alexia Kirby, Trina Dang, George Liu, Adam J Shuhendler
Methyl 5-MeO-N-aminoanthranilate, a fluorogenic probe comprising a single substituted benzene ring has been applied towards the fluorescence detection of endogenous carbonyls through rapid, catalyst-free complexation of these bio-derived markers of cell stress under physiological conditions. The products formed during the reaction between the probe and aldehydic products of lipid peroxidation, including malondialdehyde and long-chain aliphatic aldehydes relevant to the oxidative decomposition of cell membranes, have been evaluated...
November 19, 2018: Organic & Biomolecular Chemistry
Qiang Xiao, Natalie A Bécar, Nathaniel P Brown, Mason S Smith, Kimberlee L Stern, Steven R E Draper, Katherine P Thompson, Joshua L Price
Hydrocarbon stapling and PEGylation are distinct strategies for enhancing the conformational stability and/or pharmacokinetic properties of peptide and protein drugs. Here we combine these approaches by incorporating asparagine-linked O-allyl PEG oligomers at two positions within the β-sheet protein WW, followed by stapling of the PEGs via olefin metathesis. The impact of stapling two sites that are close in primary sequence is small relative to the impact of PEGylation alone and depends strongly on PEG length...
November 16, 2018: Organic & Biomolecular Chemistry
Wen-Li Wang, Dong-Rong Zhu, Jie Luo, Fei-Yan Liu, Chen Chen, Tian-Yu Zhu, Ling-Nan Li, Chao Han, Jian-Guang Luo, Ling-Yi Kong
Biogenesis-inspired chemical research of the leaves of Taiwania cryptomerioides afforded four unprecedented dimeric diterpenes, featuring a tetracyclic [7. 75, 9. 4. 05, 10. 08, 9] octodecane core: taiwanoids A-D (1-4). The structures of these compounds were determined on the basis of comprehensive spectral analysis, chemical conversions and X-ray crystallography. A possible biosynthetic pathway for compounds 1-4 was proposed. Compounds 2 and 3 exerted a 5.37 and 6.26-fold potentiation effect on bortezmib (BTZ) susceptibility at a tested concentration of 20 μM, respectively...
November 16, 2018: Organic & Biomolecular Chemistry
Yuxin Liu, Jingdong Wang, Zhonglin Wei, Jungang Cao, Dapeng Liang, Yingjie Lin, Haifeng Duan
A highly diastereo- and enantioselective Mannich reaction of isatin-derived ketimines with oxo-indanecarboxylates catalyzed by chiral thiourea derived from hydroquinidine has been developed. A series of 3-substituted 3-amino-oxindoles containing assembled bicyclic rings linked by a C-C bond were constructed by this protocol in excellent yields (92-99%) with high enantioselectivities (85-99% ee) and diastereoselectivities (up to >99 : 1 dr).
November 15, 2018: Organic & Biomolecular Chemistry
Md Nirshad Alam, Lakshmi K M, Pradip Maity
[1,2] and [2,3] Wittig rearrangements are competing reaction pathways, often leading to uncontrollable product distribution. We employ a single removable functional group to fulfill the dual role of attaining a reversible [2,3] and stabilizing radical intermediate for the [1,2] path to obtain both the Wittig products selectively for a broad range of substrates.
November 15, 2018: Organic & Biomolecular Chemistry
Scott A Geringer, Alexei V Demchenko
Glycosyl chlorides have historically been activated using harsh conditions and/or toxic stoichiometric promoters. More recently, the Ye and the Jacobsen groups showed that glycosyl chlorides can be activated under organocatalytic conditions. However, those reactions are slow, require specialized catalysts and high temperatures, but still provide only moderate yields. Presented herein is a simple method for the activation of glycosyl chlorides using abundant and inexpensive ferric chloride in catalytic amounts...
November 15, 2018: Organic & Biomolecular Chemistry
Changxing Qi, Yuben Qiao, Weixi Gao, Mengting Liu, Qun Zhou, Chunmei Chen, Yongji Lai, Yongbo Xue, Jinwen Zhang, Dongyan Li, Jianping Wang, Hucheng Zhu, Zhengxi Hu, Yuan Zhou, Yonghui Zhang
Chemical investigation of the extracts of Aspergillus terreus resulted in the identification of terreusterpenes A-D (1-4), four new 3,5-dimethylorsellinic acid-based meroterpenoids. The structures and absolute configurations of 1-4 were elucidated by spectroscopic analyses including HRESIMS and 1D- and 2D-NMR, chemical conversion, and single crystal X-ray diffraction. Terreusterpenes A (1) and B (2) featured 2,3,5-trimethyl-4-oxo-5-carboxy tetrahydrofuran moieties. Terreusterpene D (4) was characterized by a 4-hydroxy-3-methyl gamma lactone fragment that was generated by accident from the rearrangement of 3 in a mixed tetrahydrofuran-H2O-MeOH solvent...
November 15, 2018: Organic & Biomolecular Chemistry
William Copp, Derek K O'Flaherty, Christopher J Wilds
O6-Alkylguanine DNA alkyltransferases (AGTs) are proteins found in most organisms whose role is to remove alkylation damage from the O6- and O4-positions of 2'-deoxyguanosine (dG) and thymidine (dT), respectively. Variations in active site residues between AGTs from different organisms leads to differences in repair proficiency: The human variant (hAGT) has a proclivity for removal of alkyl groups at the O6-position of guanine and the E. coli OGT protein has activity towards the O4-position of thymine. A chimeric protein (hOGT) that our laboratory has engineered with twenty of the active site residues mutated in hAGT to those found in OGT, exhibited activity towards a broader range of substrates relative to native OGT...
November 15, 2018: Organic & Biomolecular Chemistry
Rebecca R Hawker, Michaela J Wong, Ronald S Haines, Jason B Harper
Correction for 'Rationalising the effects of ionic liquids on a nucleophilic aromatic substitution reaction' by Rebecca R. Hawker et al., Org. Biomol. Chem., 2017, 15, 6433-6440.
November 14, 2018: Organic & Biomolecular Chemistry
Qinghe Gao, Yakun Wang, Qianqian Wang, Yanping Zhu, Zhaomin Liu, Jixia Zhang
A facile and complementary [3 + 2 + 1] annulation of aryl ketoxime acetates and 3-formylindoles to give pyridine derivatives is reported. The condensation reaction demonstrated that I2 was capable of triggering N-O bond cleavage of ketoxime acetates to generate iminyl radicals via a single electron transfer pathway. This direct and operationally simple protocol provides a fundamental platform to synthesize 3-(4-pyridyl)indoles with high functional group compatibility and high regioselectivity.
November 14, 2018: Organic & Biomolecular Chemistry
Pei-Qian Wu, Yi-Fan Yu, Ye Zhao, Chun-Xue Yu, De-Juan Zhi, Feng-Ming Qi, Dong-Qing Fei, Zhan-Xin Zhang
Nardochinins A-D (1-4), four novel sesquiterpenoids, along with four known ones were isolated from the underground parts of Nardostachys chinensis Batal in ethanol. Their structures were determined by extensive spectroscopic methods and single-crystal X-ray diffraction. Nardochinin A (1) possessed a norsesquiterpene skeleton with an unusual 3/6/5/5 tetracyclic ring system, which had not appeared in natural products. Nardochinins B (2) and C (3) were the first time found naturally occurring sesquiterpenoids with a 4,5-seco-nardosinane skeleton...
November 14, 2018: Organic & Biomolecular Chemistry
Yue Yu, Peifeng Zheng, Yuanheng Wu, Xiaoyi Ye
Two comparable protocols for the electrochemical cobalt-catalyzed C-H/N-H oxidation have been exploited for the synthesis of substituted oxindoles via radical pathways. The electrochemical cobalt-catalyzed system was demonstrated to be efficient and eco-friendly and avoided the use of stoichiometric oxidants to afford the arylation or alkylation products in good yields at room temperature.
November 14, 2018: Organic & Biomolecular Chemistry
Geethika K Weragoda, Rowan L Pilkington, Anastasios Polyzos, Richard A J O'Hair
The combination of multistage mass spectrometry experiments employing the distonic radical approach together with DFT calculations are used to examine addition of the N-methyl-pyridinium-4-yl radical cation (γ-NMP) to iso(thio)cyanates in the gas-phase. The type of products formed depend on the nature of the iso(thio)cyanate: (1) hydrogen atom abstraction occurs for alkyl isocyanates; (2) aryl isocyanates undergo radical-ipso substitution; (3) radical attack occurs at the C[double bond, length as m-dash]C bond of allyl isocyanate; (4) radical attack occurs at the C[double bond, length as m-dash]S bond of isothiocyanates to generate S adducts of γ-NMP and isonitriles...
November 14, 2018: Organic & Biomolecular Chemistry
Naila Iqbal, Naeem Iqbal, Sung Su Han, Eun Jin Cho
Fluoroalkylated alkynes, which are versatile building blocks for the synthesis of various biologically active organofluorine compounds, were synthesized from easily available alkynyl halides and fluoroalkyl halides by visible-light photocatalysis. Addition of fluoroalkyl radicals to alkynes and subsequent dehalogenation selectively yielded fluoroalkylated alkynes.
November 14, 2018: Organic & Biomolecular Chemistry
Ali Gouranourimi, Antony Chipman, Rasool Babaahmadi, Angus Olding, Brian F Yates, Alireza Ariafard
The Nazarov cyclisation is an important and reliable reaction for the synthesis of cyclopentenones. Density functional theory (DFT) has been utilised to study the mechanism of Nazarov cyclisations initiated by oxidation of pentadienyl ethers by a benzoquinone derivative (DDQ), as recently reported by West et al. (Angew. Chem., Int. Ed., 2017, 56, 6335). We determined that the reaction is most likely initiated by a hydride transfer from the pentadienyl ether to an oxygen of DDQ through a concerted pathway and not a single electron transfer mechanism...
November 14, 2018: Organic & Biomolecular Chemistry
Tian Qin, Quanbin Jiang, Jieying Ji, Jie Luo, Xiaodan Zhao
Chiral selenide-catalyzed enantioselective trifluoromethylthiolation of 1,1-disubstituted alkenes is disclosed. By this method, a variety of chiral trifluoromethylthiolated 2,5-disubstituted oxazolines were obtained in good yields with high enantioselectivities. This work not only provides a new pathway for the synthesis of chiral oxazolines, but also expands the library of chiral trifluoromethylthiolated molecules.
November 14, 2018: Organic & Biomolecular Chemistry
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"