Aminolysis of 2,2-difluoro-4-alkoxy-1,3,2-dioxaborinanes: route to β-keto amides and β-enamino carboxamides
作者:Bogdan Štefane、Slovenko Polanc
DOI:10.1016/j.tet.2007.08.085
日期:2007.11
4-Alkoxy substituted 1,3,2-dioxaborinanes 1, readily available from β-keto esters, undergo substitution reactions under mild reaction conditions with primary and secondary amines, deriving the 4-alkylamino analogue 2. Reactions of 1 with substituted phenylhydrazines gave the corresponding hydrazones, or pyrazolones, and 5-alkoxy-1H-pyrazoles as a mixture of products.
3]-sigmatropic rearrangementreaction of α-alkylidene pyrazolinones and propargyl sulfonium salts has been reported to construct homoallyl sulfur-containing pyrazolones with moderate to excellent yields. α-Alkylidene pyrazolinones function as N-nucleophilic agents distinguished from the reported C-addition reactions. Propargyl sulfonium salts were first involved in the [2,3]-sigmatropic rearrangement protocol
Enantioselective Copper-Catalyzed [3 + 3] Cycloaddition of Tertiary Propargylic Esters with 1<i>H</i>-Pyrazol-5(4<i>H</i>)-ones toward Optically Active Spirooxindoles
作者:You-Wei Xu、Ling Li、Xiang-Ping Hu
DOI:10.1021/acs.orglett.0c03587
日期:2020.12.18
A copper-catalyzed enantioselective [3 + 3] cycloaddition of 3-ethynyl-2-oxoindolin-3-yl acetates with 1H-pyrazol-5(4H)-ones for the construction of optically active spirooxindoles bearing a spiro all-carbon quaternarystereocenter has been realized. With a combination of Cu(OTf)2 and chiral tridentate ketimine P,N,N-ligand as the catalyst, the reaction displayed broad substrate scopes, good yields
The copper-catalyzed asymmetric [3 + 3] annulation of ethynyl benzoxazinanones with pyrazolones has been achieved, providing simple access to 1,4-dihydropyrano[2,3-c]pyrazole derivatives in moderate to excellent yields with excellent enantioselectivities (up to 99% ee). Compared with previous annulation reactions of copper–allenylidenes from ethynyl benzoxazinanones, the current reaction fused the
乙炔基苯并恶嗪酮与吡唑啉酮的铜催化不对称环化[3 + 3]已实现,可轻松获得1,4-二氢吡喃并[2,3- c ]吡唑衍生物,且产率中等至优异,对映选择性极佳(高达99 %ee)。与以前的乙炔基苯并恶嗪酮的铜-亚烯基环化反应相比,当前反应将炔丙基部分的三个碳原子融合成杂环骨架。
One-Pot Asymmetric Synthesis of Spiropyrazolone-Linked Cyclopropanes and Benzofurans through a General Michael Addition/Chlorination/Nucleophilic Substitution Sequence
A sequential and general strategy has been successfully developed for the synthesis of spiropyrazolone scaffolds. This intriguing transformation of the asymmetric multicomponent catalysis process was realized with the combination of Michael addition/chlorination/nucleophilic substitution in a one-pot sequence, giving rise to a series of spiropyrazolones with fully substituted cyclopropanes and spi