共查询到19条相似文献,搜索用时 105 毫秒
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研究了醋酸铑[Rh2(OAc)4]、手性亚磺酰胺基脲和非手性磺酸共催化的α-重氮酯与酰胺化合物的不对称N—H插入反应.研究发现α-重氮酯在醋酸铑催化下形成金属卡宾,该金属卡宾与酰胺反应生成潜手性活泼叶立德中间体.在催化剂量的手性亚磺酰胺基脲和非手性磺酸存在下,潜手性叶立德中间体发生不对称质子化,合成了手性α-氨基酸衍生物.反应过程中,手性亚磺酰胺基脲和非手性磺酸作为"手性质子梭"催化不对称质子迁移从而实现了反应的对映选择性控制.该方法发展了非手性铑、手性亚磺酰胺基脲和非手性磺酸不对称共催化体系,为合成α-氨基酸衍生物提供了一种新途径,反应收率最高可达84%,对映选择性最高可达77%. 相似文献
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首次报道了方酰胺催化环状磺酰亚胺α-位的不对称胺化反应。以N-环状磺酰亚胺与偶氮二羧酸酯为原料,在方酰胺催化下经Michael加成反应构建C-N键,合成了一系列新型糖精衍生物;1-(1,1-二氧代苯并异噻唑-3-基)-1-肼二甲酸二苄酯丁烷经还原、关环反应得含尿素结构的并环衍生物,其结构经1H NMR,13C NMR和HR-MS表征。并考察了反应温度、反应时间和底物结构对胺化反应的影响。结果表明,以奎宁方酸胺为催化剂时,最佳反应条件为:二氯甲烷为溶剂,4MS为添加剂,于-30℃反应24 h,收率95%~99%,84%e.e.~94%e.e.。 相似文献
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Chiral sulfonamides derived from( d)-10-camphorsulfonyl chloride and chiral amines were prepared and used in the copper-catalyzed conjugate addition of organometallic reagents to enones. The chiral sulfonamides/CuCN catalysts provided high catalytic activity and moderate enantioselectivity in the conjugate addition of diethylzinc to 2-cyclohexenone and 2-cyclohepteneone, but low enantioselectivity to the 2-cyclopentenone and acyclic enones. 相似文献
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Baeyer-Villiger反应是有机化学基本反应之一,但是催化不对称Baeyer-Villiger反应的研究尚处于起步阶段。本文按手性配体的不同,评述了手性金属络合物催化不对称Baeyer-Villiger反应的研究,特别是由外消旋或前手性酮制备光学活性内酯的研究进展。 相似文献
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Metal carbenes derived from transition metal‐catalyzed decomposition of diazo compounds react with nucleophiles with heteroatoms, such as alcohols and amines, to generate highly active oxonium/ammonium ylides intermediates. These intermediates can be trapped by appropriate electrophiles to provide three‐component products. Based on this novel trapping process, we have developed novel multicomponent reactions (MCRs) of diazo compounds, alcohols/anilines, and electrophiles. The nucleophiles were also extended to electron‐rich heterocycles (indoles and pyrroles)/arenes, in which the resulting zwitterionic intermediates were also trapped by electrophiles. By employing efficient catalysis strategy, the reactions were realized with excellent stereocontrol and wide substrate scope. In this personal account, we introduce our breakthroughs in the development of novel asymmetric MCRs via trapping of the active ylides and zwitterionic intermediates with a number of electrophiles, such as imines, aldehyde, and Michael acceptors, under asymmetric catalysis. Transition metal/chiral Lewis acid catalysis, transition metal/Brønsted acid catalysis, and chiral transition‐metal catalysis, enable excellent stereocontrolled outcomes. The methodologies not only provide experimental evidence to support the existence of protic onium ylides intermediates/zwitterionic intermediates and the stepwise pathways of carbene‐induced O?H, N?H and C?H insertions, but also offer a novel approach for the efficient construction of chiral polyfunctional molecules. 相似文献
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The synthesis of diverse 1,4‐dihydropyridines have been achieved via the multicomponent reactions of aldehydes, enaminones and amines. The reactions have been smoothly performed in water to provide all products with moderate to excellent yields by using lactic acid as a green catalyst. 相似文献
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Kirsten A. Hewitt Claire A. Herbert Alissa C. Matus Elizabeth R. Jarvo 《Molecules (Basel, Switzerland)》2021,26(19)
Herein, we report a Kumada cross-coupling reaction of benzylic sulfonamides. The scope of the transformation includes acyclic and cyclic sulfonamide precursors that cleanly produce highly substituted acyclic fragments. Preliminary data are consistent with a stereospecific mechanism that allows for a diastereoselective reaction. 相似文献
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Mariana Ingold Victoria de la Sovera Rosina Dapueto Paola Hernndez Williams Porcal Gloria V. Lpez 《Molecules (Basel, Switzerland)》2022,27(6)
Prostate and bladder cancers are commonly diagnosed malignancies in men. Several nitric oxide donor compounds with strong antitumor activity have been reported. Thus, continuing with our efforts to explore the chemical space around bioactive furoxan moiety, multicomponent reactions were employed for the rapid generation of molecular diversity and complexity. We herein report the use of Ugi and Groebke–Blackburn–Bienaymé multicomponent reactions under efficient, safe, and environmentally friendly conditions to synthesize a small collection of nitric-oxide-releasing molecules. The in vitro antiproliferative activity of the synthesized compounds was measured against two different human cancer cell lines, LNCaP (prostate) and T24 (bladder). Almost all compounds displayed antiproliferative activity against both cancer cell lines, providing lead compounds with nanomolar GI50 values against the cancer bladder cell line with selectivity indices higher than 10. 相似文献
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Abstract An efficient, atom-economic, one-pot protocol has been developed for the synthesis of highly functionalized dihydropyridines via four-component reactions of aromatic aldehydes, arylamines, malononitrile, and dimethylacetylenedicarboxylate in the presence of sodium hydroxide in ethanol. This domino reaction proceeded smoothly in good to excellent yields and offered several advantages, including short reaction time, simple experimental procedure, and applicability to a broad range of substrates. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献