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Organic & Biomolecular Chemistry

Huanfeng Jiang, Rui Zhu, Chuanle Zhu, Fulin Chen, Wanqing Wu
An AgSCF3 mediated nucleophilic trifluoromethylthiolation reaction for C(sp)-SCF3 bond formation is reported. This nucleophilic trifluoromethylthiolation reaction of bromoalkynones afforded various useful ynonyl trifluoromethyl sulfides in high yields. Interestingly, the over-addition of AgSCF3 is avoided in our approach.
February 21, 2018: Organic & Biomolecular Chemistry
Yang Geng, Mingxiang Zhu, Apeng Liang, Chengshan Niu, Jingya Li, Dapeng Zou, Yusheng Wu, Yangjie Wu
The first O-difluorodeuteromethylation of phenols using commercial diethyl bromodifluoromethylphosphonate and deuterium oxide to prepare various difluorodeuteromethyl aryl ethers is reported. This facile method affords a convenient way to introduce OCF2 D groups into organic molecules.
February 21, 2018: Organic & Biomolecular Chemistry
Julia Weber, Marta Vaclavikova, Gerlinde Wiesenberger, Maximilian Haider, Christian Hametner, Johannes Fröhlich, Franz Berthiller, Gerhard Adam, Hannes Mikula, Philipp Fruhmann
The Fusarium metabolite culmorin (1) is receiving increased attention as an "emerging mycotoxin". It co-occurs with trichothecene mycotoxins and potentially influences their toxicity. Its ecological role and fate in plants is unknown. We synthesized sulfated and glucosylated culmorin conjugates as potential metabolites, which are expected to be formed in planta, and used them as reference compounds. An efficient procedure for the synthesis of culmorin sulfates was developed. Diastereo- and regioselective glucosylation of culmorin (1) was achieved by exploiting or preventing unexpected acyl transfer when using different glucosyl donors...
February 21, 2018: Organic & Biomolecular Chemistry
Hongze Liao, Jimei Ma, Hui Yao, Xue-Wei Liu
Chemical C-glycosylation has been well developed to improve stereoselectivity in recent years. Due to its high efficiency to build C-glycosides or O-cyclic compounds, C-glycosylation has found widespread use in the synthesis of biologically active molecules. This review highlights the C-glycosylation methods that have been practised in the total synthesis of natural products and pharmaceuticals in the past decade.
February 21, 2018: Organic & Biomolecular Chemistry
Aladin Hamoud, Philippe Barthélémy, Valérie Desvergnes
An N-Heterocyclic Carbene (NHC) catalyzed biomimetic Stetter reaction was applied for the first time as a bioconjugation reaction to sensitive nucleoside-type biomolecules to provide original pyrrole linked nucleolipids. A versatile approach allowed the functionalization of thymidine at the three reactive positions (O-5', O-3' and N-3) providing a structural diversity oriented synthesis. This strategy was applied to the synthesis of an original glyconucleolipid amphiphile in the hope that the pyrrole aromatic moiety would induce additional self-assembling properties...
February 21, 2018: Organic & Biomolecular Chemistry
Shinji Kitagaki, Kento Nakamura, Chiharu Kawabata, Asuna Ishikawa, Naoko Takenaga, Keisuke Yoshida
Planar chiral [2.2]paracyclophane-based phosphine-phenol catalysts, which have a benzene ring spacer inserted between the pseudo-ortho-substituted [2.2]paracyclophanol skeleton and the diarylphosphino group, are highly suitable for enantioselective [3 + 2] annulations of allenoates and N-tosylimines. These catalysts can be tuned by changing the substituent on the benzene rings of the diarylphosphino group. The observed enantioselectivity of 92% is the highest reported to date for phosphine-catalyzed annulations of unsubstituted allenic esters and N-tosylaldimines...
February 21, 2018: Organic & Biomolecular Chemistry
Yanshuo Zhu, Jia Guo, Shaojing Jin, Jiaomei Guo, Xuguan Bai, Qilin Wang, Zhanwei Bu
The first highly diastereoselective TfOH-catalyzed Michael addition/N,O-ketalization sequence of 3-aminooxindoles and ortho-hydroxychalcones was achieved, delivering a wide range of bridged cyclic N,O-ketal spirooxindoles with complex and strained structures in 41-97% yields. Moreover, a gram-scale experiment and some chemical conversions were conducted to further demonstrate the synthetic value.
February 20, 2018: Organic & Biomolecular Chemistry
Yi Jiang, Jiao-Xia Zou, Long-Tao Huang, Xue Peng, Jie-Dan Deng, Long-Qing Zhu, Yu-Hang Yang, Yi-Yue Feng, Xiao-Yun Zhang, Zhen Wang
An efficient and practical methodology to obtain α-thio-β-dicarbonyl compounds was presented under alkaline conditions via potassium iodide (KI) catalysis; various symmetrical/unsymmetrical 1,3-dicarbonyl compounds were obtained under an aerobic atmosphere in moderate to excellent yields, with good functional group tolerance. Notably, a widely used anti-inflammatory drug butazodine could be modified with our protocol, even on a gram scale.
February 20, 2018: Organic & Biomolecular Chemistry
Ya-Fen Yang, Wei-Bo Hu, Lei Shi, Sheng-Gang Li, Xiao-Li Zhao, Yahu A Liu, Jiu-Sheng Li, Biao Jiang, Wen Ke
pseudo[1]Catenane 3 is in a self-included conformation in chloroform, but in dichloromethane, it exists in an equilibrium between the self-included conformational state and a de-threading one. The planar chirality inversion of 3 can be triggered by the host-guest complexation of 3 with adiponitrile G, but the extent of such chiral switching depends on the length of self-included bis(pyrazin-2-yloxy)alkane chains in 3 - longer chains are more favored than shorter ones in the inversion.
February 20, 2018: Organic & Biomolecular Chemistry
Zhan-Xin Zhang, Pei-Qian Wu, Hui-Hong Li, Feng-Ming Qi, Dong-Qing Fei, Qiao-Ling Hu, Ying-Hong Liu, Xiao-Ling Huang
A novel C16 tetranorditerpenoid, norcrassin A (1), and an unusual dimeric labdane-type diterpenoid, bicrotonol A (2), were isolated from the roots of Croton crassifolius. Norcrassin A (1) featured a new carbon skeleton with an unprecedented 5/5/5/6 tetracyclic system. Bicrotonol A (2) possessed an unusual tetrahydroxypyran ring linkage connecting two labdane diterpenoid monomers. The structures of all compounds, including the absolute configuration, were elucidated by the interpretation of their NMR spectroscopic data, high resolution mass spectrometry, and single-crystal X-ray diffraction...
February 20, 2018: Organic & Biomolecular Chemistry
Xiao-Fang Li, Xing-Guo Zhang, Bo-Lun Hu, Xiao-Hong Zhang
A straightforward method for the synthesis of polyfunctionalized quinolines from readily available N-aryl propargylamines under aerobic conditions was developed. It provides convenient access to a variety of synthetically and pharmaceutically important quinolines in moderate to good yields. Control experiments suggest that the cascade reaction might proceed via the Pd-catalyzed electrophilic cyclization of N-aryl propargylamines followed by a hydroarylation process through trapping of the σ-quinolinylpalladium intermediate with a second molecule of the substrate...
February 20, 2018: Organic & Biomolecular Chemistry
Maruthi Konda, Rohit G Jadhav, Sayan Maiti, Shaikh M Mobin, Brice Kauffmann, Apurba K Das
Constrained γ-amino acid gababutin (Gbn) based peptides that form different conformations have been synthesized. Striving to rationalize the impact of side chain orientations framing tetrapeptide-based supramolecular organic frameworks and morphological entities, Gbn incorporated hybrid peptides Boc-Gbn-Aib-Aaa-Aib-OMe (where Aaa = Phe(F) for peptide 1, Leu(L) for peptide 2 and Tyr(Y) for peptide 3) were synthesized by changing the amino acid at the third position. The solution state dual folded conformation (C12 /C10 H-bonded) is probed by 2D NMR spectroscopy in support of a DMSO-d6 titration and VT NMR experiments...
February 19, 2018: Organic & Biomolecular Chemistry
Kavitha Donthiboina, Hari Krishna Namballa, Siddiq Pasha Shaik, Jagadeesh Babu Nanubolu, Nagula Shankaraiah, Ahmed Kamal
An iodine promoted tandem oxidative condensation of benzylamines and 2-methylquinazolin-4-(3H)-ones was developed to yield imidazo[1,5-a]quinazolin-5(4H)-ones via dual C(sp3 )-H amination under metal free conditions in a greener way using molecular oxygen as a terminal oxidant. This tandem transformation provides an efficient approach to construct various functionalized imidazo[1,5-a]quinazolin-5(4H)-ones in a straightforward manner via a sequential amination-oxidation-annulation-aromatisation.
February 19, 2018: Organic & Biomolecular Chemistry
Zhen-Hua Wang, Yong You, Yong-Zheng Chen, Xiao-Ying Xu, Wei-Cheng Yuan
An asymmetric organocatalytic vinylogous Mannich reaction of 3-methyl-5-arylfuran-2(3H)-ones with N-(2-pyridinesulfonyl)imines has been developed with 5 mol% thiourea-tertiary amine as the catalyst. A series of δ-amino γ,γ-disubstituted butenolides bearing adjacent quaternary and tertiary stereocenters are efficiently obtained with satisfactory results (up to 90% yield, 90 : 10 dr, and 95 : 5 er).
February 16, 2018: Organic & Biomolecular Chemistry
Tal Eilon-Shaffer, Michal Roth-Konforti, Anat Eldar-Boock, Ronit Satchi-Fainaro, Doron Shabat
A recent methodology, developed by our group, has enabled a dramatic improvement in the emissive nature of the excited species, formed during the chemiexcitation of dioxetanes under physiological conditions. This approach has resulted in the discovery of distinct phenoxy-dioxetane luminophores that produce a chemiluminescence signal via a direct-mode of emission. Here, we show a significant pK a effect of our new phenoxy-dioxetanes on their chemiexcitation and on their ability to serve as chemiluminescent turn-ON probes for biological applications...
February 16, 2018: Organic & Biomolecular Chemistry
Qian Chen, Yulin Huang, Xiaofeng Wang, Jiawei Wu, Guodian Yu
A highly efficient sulfonylation of thiols has been achieved through the metal-free NaI/TBHP-mediated cross-coupling of sulfonyl hydrazides and thiols at room temperature. This method provides a convenient and practical route to thiosulfonates in 84-99% yields (39 examples) with wide functional group compatibility.
February 16, 2018: Organic & Biomolecular Chemistry
D L Obydennov, L R Khammatova, O S Eltsov, V Y Sosnovskikh
Chemo- and regiocontrolled syntheses of pyrazoles and pyridones are presented on the basis of 4-pyrones. A novel approach towards highly functionalized 3,4'-bipyrazoles has been developed by using reactions of ethyl 5-acylcomanoates with hydrazines. The acid-promoted double cyclocondensation allows switching of the structure of the pyrazole rings easily through changing both the nature of hydrazine and the reaction conditions. The transformation of 4-pyrones with phenylhydrazine in EtOH at -20 °C leads to hydroxypyridones as monoaddition products which can be used as precursors for the preparation of pyridone and pyrazole derivatives...
February 16, 2018: Organic & Biomolecular Chemistry
Jin-Bao Peng, Bo Chen, Xinxin Qi, Jun Ying, Xiao-Feng Wu
Quinolin-2(1H)-one is a useful structure unit present in a wide range of natural products and pharmaceuticals. A Pd(ii)-catalyzed synthesis of quinolin-2(1H)-ones from quinoline N-oxides was developed with azodicarboxylates which act as both the activating agent and oxidant. The reaction proceeded under mild conditions and no protection against air and moisture was needed.
February 16, 2018: Organic & Biomolecular Chemistry
Guilherme A M Jardim, Willian X C Oliveira, Rossimiriam P de Freitas, Rubem F S Menna-Barreto, Thaissa L Silva, Marilia O F Goulart, Eufrânio N da Silva Júnior
We report a sequential C-H iodination/organoyl-thiolation of naphthoquinones and their relevant trypanocidal activity. Under a combination of AgSR with a copper source, sulfur-substituted benzenoid quinones were prepared in high yields (generally >90%). This provides an efficient and general method for preparing A-ring modified naphthoquinoidal systems, recognized as a challenge in quinone chemistry.
February 16, 2018: Organic & Biomolecular Chemistry
Xiaoyu Xing, Yan Zhao
Conformational flexibility in the host's structure is often considered detrimental to its binding. Flexible pseudo-crown ethers with aromatic donor/acceptor groups at the chain ends, however, displayed enhanced binding affinity and selectivity, particularly when the direct binding interactions were compromised by unfavorable solvents.
February 15, 2018: Organic & Biomolecular Chemistry
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