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181.
The total synthesis of (±)-meloscine was completed in a highly stereoselective manner starting from the known 4-(2-aminophenyl)-2,3-dihydro-N-methoxycarbonylpyrrole. The crucial step in this total synthesis involves the efficient construction of the tetracyclic framework of the target natural product by the intramolecular Pauson-Khand reaction. 相似文献
182.
The Stille coupling reaction of 3-(benzyloxymethyl)-1-(tert-butyldiphenylsiloxy)ethyl-1-(tributylstannyl)allene with N-(tert-butoxycarbonyl)-2-iodoaniline directly produced the corresponding 2-vinylindole derivative, which was independently transformed into natural (-)-goniomitine and unnatural (+)-goniomitine via the cross-metathesis with chiral oxazolopiperidone lactams. The antiproliferative activity of the synthesized natural (-)-goniomitine in Mock and MDCK/MDR1 cells showed them to be more potent to retard cell growth than unnatural (+)-goniomitine. 相似文献
183.
184.
Dr. Fukai Xie Zhan Mao Dr. Dennis P. Curran Hongliang Liang Dr. Wen Dai 《Angewandte Chemie (International ed. in English)》2023,62(39):e202306846
Although the development of radical chain and photocatalytic borylation reactions using N-heterocyclic carbene (NHC)-borane as boron source is remarkable, the persistent problems, including the use of hazardous and high-energy radical initiators or the recyclability and photostability issues of soluble homogeneous photocatalysts, still leave great room for further development in a sustainable manner. Herein, we report a conceptually different approach toward highly functionalized organoborane synthesis by using recoverable ultrathin cadmium sulfide (CdS) nanosheets as a heterogeneous photocatalyst, and a general and mild borylation platform that enables regioselective borylation of a wide variety of alkenes (arylethenes, trifluoromethylalkenes, α,β-unsaturated carbonyl compounds and nitriles), alkynes, imines and electron-poor aromatic rings with NHC-borane as boryl radical precursor. Mechanistic studies and density functional theory (DFT) calculations reveal that both photogenerated electrons and holes on the CdS fully perform their own roles, thereby resulting in enhancement of photocatalytic activity and stability of CdS. 相似文献
185.
Jun Manabe Nagisa Sako Mizuki Ito Dr. Masaru Fujibayashi Dr. Chisato Kato Dr. Goulven Cosquer Prof. Katsuya Inoue Dr. Kiyonori Takahashi Prof. Takayoshi Nakamura Prof. Tomoyuki Akutagawa Dr. Seiya Shimono Dr. Hiroki Ishibashi Prof. Yoshiki Kubota Prof. Sadafumi Nishihara 《欧洲无机化学杂志》2023,26(34):e202300449
Materials exhibiting irreversible phase transitions, leading to changes in their properties, have a potential for novel application in electronic components such as a non-rewritable high-security memory. Here, we focused on the two salts, [(9-triptycylammonium)([18]crown-6)][Ni(dmit)2] ( 1 ) and [(9-triptycylammonium)([15]crown-5)][Ni(dmit)2] ( 2 ), which featured 2D sheet structures with alternately stacked cation and anion layers. Both salts exhibit similar cation arrangements, however, their anion arrangements differ significantly. The temperature-dependent magnetic susceptibilities of 1 and 2 were well reproduced by the alternating chain model (JAC1/kB=−306(8), JAC2/kB=−239(3) K) and the Curie-Weiss model (θ=−3.9(1) K), respectively. 1 experience a reversible phase transition around 40–60 K, causing anomalies in magnetic behavior. Moreover, an irreversible single-crystal-to-single-crystal phase transition to 1′ undergo at ~381 K, inducing a rearrangement of [Ni(dmit)2]− anions and a resistivity decrease from 6.5×106 to 6.5×102 Ω cm. The susceptibility curve of 1′ was reproduced by a combination of the Curie-Weiss and dimer models (Jdimer/kB=−407(5), θ=−26.7(5) K). The irreversible transition of 1 is the first example for such supramolecule and [Ni(dmit)2]− system to our knowledge, in opening potential new-type materials. 相似文献