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Science China Mathematics - We study the toric degeneration of Weyl group translated Schubert divisors of a partial flag variety $$F{\ell _{{n_1}, \ldots,{n_k};n}}$$ via Gelfand-Cetlin polytopes.... 相似文献
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Heejeong Choi Il Young Ryu Inkyu Choi Sultan Ullah Hee Jin Jung Yujin Park Yeongmu Jeong YeJi Hwang Sojeong Hong In-Soo Yoon Hwayoung Yun Min-Soo Kim Jin-Wook Yoo Yunjin Jung Pusoon Chun Hyung Ryong Moon 《Molecules (Basel, Switzerland)》2021,26(16)
To confirm that the β-phenyl-α,β-unsaturated thiocarbonyl (PUSTC) scaffold, similar to the β-phenyl-α,β-unsaturated carbonyl (PUSC) scaffold, acts as a core inhibitory structure for tyrosinase, twelve (Z)-5-(substituted benzylidene)-4-thioxothiazolidin-2-one ((Z)-BTTZ) derivatives were designed and synthesized. Seven of the twelve derivatives showed stronger inhibitory activity than kojic acid against mushroom tyrosinase. Compound 2b (IC50 = 0.47 ± 0.97 µM) exerted a 141-fold higher inhibitory potency than kojic acid. Kinetic studies’ results confirmed that compounds 2b and 2f are competitive tyrosinase inhibitors, which was supported by high binding affinities with the active site of tyrosinase by docking simulation. Docking results using a human tyrosinase homology model indicated that 2b and 2f might potently inhibit human tyrosinase. In vitro assays of 2b and 2f were conducted using B16F10 melanoma cells. Compounds 2b and 2f significantly and concentration-dependently inhibited intracellular melanin contents, and the anti-melanogenic effects of 2b at 10 µM and 2f at 25 µM were considerably greater than the inhibitory effect of kojic acid at 25 µM. Compounds 2b and 2f similarly inhibited cellular tyrosinase activity and melanin contents, indicating that the anti-melanogenic effects of both were due to tyrosinase inhibition. A strong binding affinity with the active site of tyrosinase and potent inhibitions of mushroom tyrosinase, cellular tyrosinase activity, and melanin generation in B16F10 cells indicates the PUSTC scaffold offers an attractive platform for the development of novel tyrosinase inhibitors. 相似文献
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Kim NJ Moon H Park T Yun H Jung JW Chang DJ Kim DD Suh YG 《The Journal of organic chemistry》2010,75(21):7458-7460
The concise and enantioselective synthesis of 15-deoxy-Δ(12,14)-prostaglandin J(2) (15d-PGJ(2)) has been accomplished in 11 steps from a known alcohol. The key step of the synthesis involves an asymmetric Rh-catalyzed cycloisomerization of ene-ynone, followed by an olefin isomerization. 相似文献
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The first total synthesis of 6-hydroxy-7-(hydroxymethyl)-4-methylenehexahydrocyclopenta[c]pyran-1(3H)-one has been accomplished. A key feature of the synthesis includes facile construction of the bicyclic lactone intermediate via intramolecular Pd(0)-catalyzed allylic alkylation and the efficient transformation of this intermediate into the iridoid skeleton employing silicon tethered radical cyclization. 相似文献
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Suh YG Lee YS Kim SH Jung JK Yun H Jang J Kim NJ Jung JW 《Organic & biomolecular chemistry》2012,10(3):561-568
A novel and stereo-controlled method for the preparation of functionalized macrolactams was developed. The process involves stereoselective enol ether formation, followed by an azacyclic ring expansion via an aza-Claisen rearrangement. Herewith, we describe a systematic investigation of an aza-Claisen rearrangement-induced ring expansion of azacycles prepared by appending E/Z-enol ethers to the medium-sized lactams as well as the stereochemical outcome. In addition, the strategy was successfully applied to the total synthesis of fluvirucinine A(1) and 3-epi-fluvirucinine A(1). This method offers an attractive alternative to the intramolecular amide-aldol reaction for the elaboration of β-alkoxy-α-substituted motifs. 相似文献
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Dr. Jin Hee Lee Seul‐gi Park Kyeojin Kim Changjin Lim Dr. Young Taek Han Dr. Hwayoung Yun Prof. Jong‐Wha Jung Prof. Hyeung‐geun Park Prof. Hee‐Doo Kim Byoung Young Woo Dr. Song Seok Shin Dr. Sun‐Young Kim Jin Kyu Choi Yeon‐Su Jeong Yanghui Park Dr. Young‐Ho Park Prof. Dae‐Duk Kim Prof. Sun Choi Prof. Young‐Ger Suh 《化学:亚洲杂志》2013,8(2):400-409
A series of heterocycle‐linked constrained phenylbenzyl amides were found to be TRPV1 antagonists with promising in vivo profiles. In particular, one of the analogues containing a furan linker exhibited excellent TRPV1 antagonistic activity and in vivo analgesic efficacy. In addition, the binding modes of dibenzyl thiourea, benzylphenethyl amide, and furan‐linked phenylbenzyl amide were examined by using the flexible docking study within the rTRPV1 homology model. 相似文献
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A highly stereoselective and efficient method for the synthesis of optically active homoallylamines was developed. Key features of the method include (1) the utilization of naphthylethylamine as both an excellent chiral auxiliary and the amine source, (2) the 1,3-chiral induction of the N-acyliminium ion with high stereoselectivity and high yield, and (3) facile auxiliary removal under mild conditions to liberate N-Cbz-protected homoallylamines. In addition, the total synthesis of the proposed novel tripeptide containing a β-amino acid has been achieved by applying this method. 相似文献
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A concise and high-yielding protocol for the synthesis of 5,6-dihydrophenanthridines is disclosed. The key feature includes a sequential reduction-cyclization reaction of N-acylcarbamates via N,O-acetal TMS ethers as a stable N-acyliminium ion precursor. 相似文献
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Yun H Kim J Sim J Lee S Han YT Chang DJ Kim DD Suh YG 《The Journal of organic chemistry》2012,77(12):5389-5393
Asymmetric syntheses of both 1-deoxy-6,8a-di-epi-castanospermine and 1-deoxy-6-epi-castanospermine, polyhydroxylated indolizidine alkaloids that act as selective glycosidase inhibitors, have been accomplished in seven steps. The key feature of our unique syntheses includes the stereoselective introduction of the C-3 and C-4 hydroxyl groups utilizing the aza-Claisen rearrangement-induced ring expansion of 1-acyl-2-alkoxyvinyl pyrrolidine and a substrate-controlled stereoselective transannulation of the resulting azoninone intermediate. 相似文献
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