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901.
902.
Dr. Brijesh M. Sharma Dr. Arun V. Nikam Dr. Santosh Lahore Gwang-Noh Ahn Prof. Dr. Dong-Pyo Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(20):e202103777
This work reports a cyanide-free continuous-flow process for cyanation of sp2 and sp carbons to synthesize aryl, vinyl and acetylenic nitriles from (5-methyl-2-phenyloxazol-4-yl) boronic acid [OxBA] reagent as a sole source of carbon-bound masked −CN source. Non-toxic and stable OxBA reagent is generated by lithiation-borylation of bromo-oxazole, and the consecutive Suzuki-Miyaura cross-coupling with aryl, vinyl, or acetylenic halides and demasking [4+2]/retro-[4+2] sequence were successfully accomplished to give the desired cyano compounds with reasonably good yields in a four-step flow manner. A unique feature of this cyanation protocol in flow enables to cyanate a variety of sp2 and sp carbons to produce a broad spectrum of aryl acetonitrile. It is envisaged that the OxBA based cyanation would replace existing unstable and toxic approaches as well as non-toxic cyanation using two different sources of “C” and “N” to incorporate the −CN group. 相似文献
903.
Jung-Kyun Woo Jung-Ho Yun Seyeon Ahn Chung J. Sim Minsoo Noh Dong-Chan Oh Ki-Bong Oh Jongheon Shin 《Tetrahedron letters》2018,59(21):2021-2024
Dictyoneolone (1), a new secosteroid was isolated from a Dictyonella sp. sponge collected from Gageo-do, Korea. Based upon the results of combined spectroscopic analyses, the structure of this compound was determined to possess a highly unusual B/C ring juncture-defused moiety. The configurations of 1 were determined by a combination of proton-proton couplings and NOESY analyses. Dictyoneolone exhibited weak cytotoxicity against the K562 and A549 cancer cell lines. 相似文献
904.
Eun Ji Kim Jungmin Ahn Haeri Lee Tae Hwan Noh Ok-Sang Jung 《Tetrahedron letters》2012,53(10):1240-1244
4-tert-Butylcalix[n]arenes react with an excess of (iso)nicotinoyl chloride, yielding selectively n-2 acylated products, calix[n]-(nico)n?2(OH)2, (calix = 4-tert-butylcalix[n]arene; n = 4, 6, and 8; nico = (iso)nicotinoylate) of alternate conformations. Their structures were determined by X-ray single crystallography and NMR spectra. The UV–vis spectra indicated that a new absorption band of the complexes appears upon the addition of cobalt(II) dichloride, and its crystal structure was resolved. 相似文献
905.
Hyeohn Kim Sang Won Im Nam Heon Cho Da Hye Seo Ryeong Myeong Kim Yae-Chan Lim Dr. Hye-Eun Lee Dr. Hyo-Yong Ahn Prof. Ki Tae Nam 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):13076-13083
Chiral optical metamaterials with delicate structures are in high demand in various fields because of their strong light–matter interactions. Recently, a scalable strategy for the synthesis of chiral plasmonic nanoparticles (NPs) using amino acids and peptides has been reported. Reported herein, 3D chiral gold NPs were synthesized using dipeptide γ-Glu-Cys and Cys-Gly and analyzed crystallographically. The γ-Glu-Cys-directed NPs present a cube-like outline with a protruding chiral wing. In comparison, the NPs synthesized with Cys-Gly exhibited a rhombic dodecahedron-like outline with curved edges and elliptical cavities on each face. Morphology analysis of intermediates indicated that γ-Glu-Cys generated an intermediate concave hexoctahedron morphology, while Cys-Gly formed a concave rhombic dodecahedron. NPs synthesized with Cys-Gly are named 432 helicoid V because of their unique morphology and growth pathway. 相似文献
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910.
Se Jeong Kwon Dohee Ahn Hyun-Mo Yang Hyo Jin Kang Sang J. Chung 《Molecules (Basel, Switzerland)》2021,26(4)
Natural products have continued to offer tremendous opportunities for drug development, as they have long been used in traditional medicinal systems. SHP2 has served as an anticancer target. To identify novel SHP2 inhibitors with potential anticancer activity, we screened a library containing 658 natural products. Polyphyllin D was found to selectively inhibit SHP2 over SHP1, whereas two other identified compounds (echinocystic acid and oleanolic acid) demonstrated dual SHP1 and SHP2 inhibition. In a cell-based assay, polyphyllin D exhibited cytotoxicity in Jurkat cells, an acute lymphoma leukemia cell line, whereas the other two compounds were ineffective. Polyphyllin D also decreased the level of phosphorylated extracellular signal-regulated kinase (p-ERK), a proliferation marker in Jurkat cells. Furthermore, knockdown of protein tyrosine phosphatase (PTP)N6 (SHP1) or PTPN11 (SHP2) decreased p-ERK levels. However, concurrent knockdown of PTPN6 and PTPN11 in Jurkat cells recovered p-ERK levels. These results demonstrated that polyphyllin D has potential anticancer activity, which can be attributed to its selective inhibition of SHP2 over SHP1. 相似文献