acid/base-free domino process is developed for the regioselective synthesis of 1,2,4-trisubstituted pyrroles. The process involves 1,3-dipolar cycloaddition of unsymmetrical azomethine ylide resulting from the thermal C–C bond cleavage of unactivated aziridines with β-bromo-β-nitrostyrene, followed by a cascade of elimination and aromatization reaction sequence to preferentially furnish 1,2,4-trisubstituted
Copper-catalyzed routes have been achieved for the synthesis of 3-nitroquinolines from readily available nitroolefins and anthranils. This reaction proceeds via the [4+2] cycloaddition between anthranils and nitro-styrenes under mild reaction conditions to obtain biologically important heterocycles. A wide range of diversely substituted nitro-olefins and anthranils are successfully employed in this
chemoselective conjugate reduction of electron-deficient Michael acceptors, including alpha,beta-unsaturated ketones, carboxylic esters, nitriles and nitro compounds with PMHS in the presence of catalytic B(C6F5)3 is described.
3-Halo-5,6-dihydro-4<i>H</i>-1,2-oxazine <i>N</i>-oxides as synthetic equivalents of unsaturated nitrile oxides in the [3 + 2]-cycloaddition with arynes: synthesis of substituted 3-vinyl-1,2-benzisoxazoles
作者:Alexander A. Lukoyanov、Svetlana A. Aksenova、Andrey A. Tabolin、Alexey Yu. Sukhorukov
DOI:10.1039/d4ob00391h
日期:——
The reaction of 3-halo-5,6-dihydro-4H-1,2-oxazine N-oxides with arynes was studied. Arynes were generated from o-silylaryl triflates and underwent consecutive [3 + 2]-cycloaddition/[4 + 2]-cycloreversion with N-oxides leading to substituted 3-vinyl-benzisoxazoles in high yields. In the presented sequence, 1,2-oxazine N-oxides act as surrogates of rarely employedunsaturated nitrile oxides. A broad
研究了3-卤代-5,6-二氢-4H -1,2-恶嗪N-氧化物与芳烃的反应。芳烃由邻甲硅烷基芳基三氟甲磺酸酯生成,并与N-氧化物进行连续的[3 + 2]-环加成/[4 + 2]-环化还原,以高产率产生取代的3-乙烯基-苯并异恶唑。在所提出的序列中,1,2-恶嗪N-氧化物充当很少使用的不饱和腈氧化物的替代物。展示了广泛的底物范围。确定了芳基的取代模式对反应结果的影响。在大取代基存在下,选择性地形成多环4,4a-二氢-3H-苯并呋喃并[3,2- c ][1,2]恶嗪。提出了观察到的反应途径的机理方案。产品的合成实用性通过其后续修饰得到了证明。
Consecutive Cycloaddition/S<sub>N</sub>Ar/Reduction/Cyclization/Oxidation Sequences: A Copper-Catalyzed Multicomponent Synthesis of Fused N-Heterocycles
A highly efficient multicomponent domino protocol has been developed for the synthesis of 5-phenyl-[1,2,3]triazolo[1,5-c]quinazolines from simple and readily available (E)-1-bromo-2-(2-nitrovinyl)benzenes, aldehydes, and sodium azide. This elegant domino process involved consecutive [3 + 2] cycloaddition, copper-catalyzed SNAr, reduction, cyclization, and oxidation sequences. Notably, sodium azide acted as a dual nitrogen source in the construction of this novel fused N-heterocycle.