排序方式: 共有40条查询结果,搜索用时 15 毫秒
31.
(E)‐ and (Z)‐5‐(bromomethylene)furan‐2(5H)‐one have been prepared starting from the commercially available adduct between furan and maleic anhydride. A bromodecarboxylation reaction is a key step in the synthesis. The reaction gives the (E)‐ or (Z)‐5‐(bromomethylene)furan‐2(5H)‐one as the major product, dependent on the method used in the bromodecarboxylation. 相似文献
32.
Direct Catalytic Asymmetric Vinylogous Additions of α,β‐ and β,γ‐Butenolides to Polyfluorinated Alkynyl Ketimines
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Prof.?Dr. Barry M. Trost Chao‐I. Hung Manuel J. Scharf 《Angewandte Chemie (International ed. in English)》2018,57(35):11408-11412
We report a Zn‐ProPhenol catalyzed asymmetric Mannich reaction between butenolides and polyfluorinated alkynyl ketimines to obtain vinylogous products featuring two contiguous tetrasubstituted stereogenic centers. Notably, this is the first successful use of ketimines in the ProPhenol Mannich process, and the reaction offers a new approach for the preparation of pharmaceutically relevant products possessing trifluoromethylated tetrasubstituted alkylamines. The reaction can be performed on large scale with reduced catalyst loading without impacting its efficiency. Moreover, the acetylene moiety can be further elaborated using various methods. 相似文献
33.
Feng Li Jingjing Wang Wenlong Pei Hai Ma Hong Li Mingyue Cui Shuxin Peng Shihui Wang Lantao Liu 《Tetrahedron letters》2018,59(31):3010-3014
An efficient Et3N-catalyzed alkenylation of γ-substituted deconjugated butenolides with cyclic N-sulfonylated imines in water is described. The reaction proceeds efficiently under mild reaction conditions to give α-arylidene butenolide derivatives in high yield (82–96%). 相似文献
34.
Utilizing aldol condensation and β-elimiation as the key steps,butenolides I and Ⅱ in excellent enantiomeric purity have been concisely synthesized for the first time.According to the ratation difference between synthetic samples and natural products,the rotations were corrected by the calculation upon HPLC measurements.In addition,an efficient way to synthesize methyl pentadec-14-enoate was developed. 相似文献
35.
Ibrahim Seyda Uras Sherif S. Ebada Michal Korinek Amgad Albohy Basma S. Abdulrazik Yi-Hsuan Wang Bing-Hung Chen Jim-Tong Horng Wenhan Lin Tsong-Long Hwang Belma Konuklugil 《Molecules (Basel, Switzerland)》2021,26(11)
In December 2020, the U.K. authorities reported to the World Health Organization (WHO) that a new COVID-19 variant, considered to be a variant under investigation from December 2020 (VUI-202012/01), was identified through viral genomic sequencing. Although several other mutants were previously reported, VUI-202012/01 proved to be about 70% more transmissible. Hence, the usefulness and effectiveness of the newly U.S. Food and Drug Administration (FDA)-approved COVID-19 vaccines against these new variants are doubtfully questioned. As a result of these unexpected mutants from COVID-19 and due to lack of time, much research interest is directed toward assessing secondary metabolites as potential candidates for developing lead pharmaceuticals. In this study, a marine-derived fungus Aspergillus terreus was investigated, affording two butenolide derivatives, butyrolactones I (1) and III (2), a meroterpenoid, terretonin (3), and 4-hydroxy-3-(3-methylbut-2-enyl)benzaldehyde (4). Chemical structures were unambiguously determined based on mass spectrometry and extensive 1D/2D NMR analyses experiments. Compounds (1–4) were assessed for their in vitro anti-inflammatory, antiallergic, and in silico COVID-19 main protease (Mpro) and elastase inhibitory activities. Among the tested compounds, only 1 revealed significant activities comparable to or even more potent than respective standard drugs, which makes butyrolactone I (1) a potential lead entity for developing a new remedy to treat and/or control the currently devastating and deadly effects of COVID-19 pandemic and elastase-related inflammatory complications. 相似文献
36.
37.
《Tetrahedron》2003,59(18):3237-3251
The four furanones (butenolides) 1-4, which had been isolated from the fermentation broth of Streptomyces antibioticus TÜ 99 and in preliminary tests had been shown to be biologically active, were synthesized by reaction of the readily available furanones 9 or 16 with 2-methylpropanal or 2-methylbutanal. In addition, a series of analogs was prepared in a similar way from 16 using different aldehydes. The hitherto unknown absolute configurations of the natural products 1-4 as well as those of all the analogs prepared were determined with Mosher's NMR method and/or X-ray crystallography. Some of the compounds synthesized proved to be active in the quorum sensing system of Chromobacterium violaceum. 相似文献
38.
39.
Laxmaiah Vasamsetty Debashis Sahu Bishwajit Ganguly Faiz Ahmed Khan Goverdhan Mehta 《Tetrahedron》2014
A short and generally applicable synthesis of bioactive tetracyclic natural product paracaseolide A has been accomplished employing a ‘proposed’ biomimetic Diels–Alder reaction as the key strategic step. The Diels–Alder precursors for this purpose were readily assembled through a versatile Suzuki coupling on preformed α-halo butenolides. The mechanistic aspects of the ‘putative’ biomimetic Diels–Alder reaction have been probed using computational methods, which suggest that this [4+2]-cycloaddition proceeds through a step-wise process and product profile is thermodynamically governed. 相似文献
40.