- Competition between the donor and acceptor hydrogen bonds of the threads in the formation of [2]rotaxanes by clipping reaction
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The synthesis of benzylic amide [2]rotaxanes using 1,2-bis(aminocarbonyl-(1′-tert-butyl-1H-pyrazole-[3′]5′-yl))-ethanes as templates is reported. These templates are equipped with tert-butyl pyrazole-based stoppers and have donor (N-H) and acceptor (CO) hydrogen bond groups. The synthesis of [2]rotaxanes has been shown to be highly dependent on the tert-butylpyrazole stoppers. While the thread with 1′,3′-disubstituted pyrazoles as stopper units was shown to be an excellent template for the synthesis of [2]rotaxanes, the thread with 1′,5′-disubstituted pyrazoles as stopper units did not yield the expected [2]rotaxane. The structure of the synthesized [2]rotaxanes was characterized using NMR experiments and X-ray diffraction, with the latter showing that the macrocycle adopts a distorted chair conformation. An in-depth study of the isolated thread's X-ray structures and concentration-dependent NMR experiments seem to explain the dependence of the rotaxane formation on the substitution pattern of the thread's pyrazole stoppers.
- Martins, Marcos A. P.,Zimmer, Geórgia C.,Rodrigues, Leticia V.,Orlando, Tainára,Buriol, Lilian,Alajarin, Mateo,Berna, Jose,Frizzo, Clarissa P.,Bonacorso, Helio G.,Zanatta, Nilo
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p. 13303 - 13318
(2017/11/27)
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- Regio-specific synthesis of new 1-(tert-butyl)-1H-pyrazolecarboxamide derivatives
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Regio-specific and non-regiospecific condensation reactions on 1,3-dicarbonyl compounds rendered 1,3,5-trisubstituted pyrazoles. Herein, the control of regio-specificity was a significant improvement in pyrazole research. A high yield acylation of poorly
- Ruatta, Santiago Matías,Murguía, Marcelo César,Ramírez de Arellano, Carmen,Fustero, Santos
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supporting information
p. 2441 - 2444
(2017/06/05)
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- New analogues of (E)-β-farnesene with insecticidal activity and binding affinity to aphid odorant-binding proteins
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(E)-β-Farnesene is a strong and efficient alarm pheromone in most aphid species. However, applications in agriculture are prevented by its relatively high volatility, its susceptibility to oxidation and its complex and expensive synthesis. To develop novel compounds for aphid control, we have designed and synthesized analogues of (E)-β-farnesene, containing a pyrazole moiety present in several insecticides. Their structures have been confirmed by 1H NMR, elemental analysis, high-resolution mass spectroscopy and IR. Binding activities to three odorant-binding proteins (OBPs) of the pea aphid Acythosiphon pisum have been evaluated and correlated with their structures with reference to (E)-β-farnesene. Several derivatives were shown both to bind to A. pisum OBPs with a specificity similar to that of (E)-β-farnesene and to have aphicidal activity comparable to that of thiacloprid, a commercial insecticide. The compounds synthesized in this work represent new potential agents for aphid population control and provide guidelines to design analogues of (E)-β-farnesene endowed with both insecticidal and repellent activity for aphids.
- Sun, Yufeng,Qiao, Huili,Ling, Yun,Yang, Shaoxiang,Rui, Changhui,Pelosi, Paolo,Yang, Xinling
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experimental part
p. 2456 - 2461
(2011/10/12)
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