Silver(I)‐ and Base‐Mediated formal [4+3] Cycloaddition of
<i>in Situ</i>
generated 1,2‐Diaza‐1,3‐dienes with
<i>C,N</i>
‐Cyclic Azomethine Imines: An Efficient Protocol for the Synthesis of Tetrazepine Derivatives
作者:Zefei Li、Shuaikang Li、Tianjiao Kan、Xinyue Wang、Xin Xin、Yunlei Hou、Ping Gong
DOI:10.1002/adsc.202000398
日期:2020.7.16
A silver(I)‐ and base‐mediated formal [4+3] cycloadditionreaction of in situ generated 1,2‐diaza‐1,3‐dienes with in situ formed C,N‐cyclic azomethine imines has been developed. This protocol provided an efficient method for the synthesis of biologically important 1,2,4,5‐tetrazepine derivatives with a wild substrate scope and excellent functional group tolerance in moderate to excellent yields.
Sequential MCR via Staudinger/Aza-Wittig versus Cycloaddition Reaction to Access Diversely Functionalized 1-Amino-1H-Imidazole-2(3H)-Thiones
作者:Cecilia Ciccolini、Giacomo Mari、Gianfranco Favi、Fabio Mantellini、Lucia De Crescentini、Stefania Santeusanio
DOI:10.3390/molecules24203785
日期:——
the known cycloaddition reaction, towards variously substituted 1-amino-1H-imidazole-2(3H)-thione derivatives has been successfully developed. The novel approach involves α-halohydrazones whose azidation process followed by tandem Staudinger/aza-Wittig reaction with CS2 in a sequential MCR regioselectively leads to the target compounds avoiding the formation of the regioisomer iminothiazoline heterocycle
Cycloaddition reactions of nitrosoalkenes, azoalkenes and nitrile oxides mediated by hydrotalcite
作者:Americo Lemos、João Paulo Lourenço
DOI:10.3998/ark.5550190.0011.515
日期:——
Mg:Al 3:1 hydrotalcite (Ht), used in catalytic quantities, promotes the generation of nitrosoalkenes, azoalkenes and nitrile oxides. These can be intercepted in situ by heterocycles and olefins in [4+2] and [3+2] cycloadditionreactions, producing dihydro-1,2-oxazines, tetrahydropyridazines and isoxazolines. The regeneration and reuse of Ht without loss of activity and the absence of organic solvent
Addition of malonic esters to azoalkenes generated in situ from α-bromo- and α-chlorohydrazones
作者:Aleksandr O. Kokuev、Sema L. Ioffe、Alexey Yu. Sukhorukov
DOI:10.1016/j.tetlet.2021.153414
日期:2021.10
Michael addition of malonicesters to azoalkenes generated in situ from α-bromo- and α-chlorohydrazones was accomplished. Both aliphatic and aromatic substrates bearing different functional groups are tolerated. The use of a strong base (sodium hydride) for generation of azoalkenes and deprotonation of malonate was found to be essential for a successful coupling. Synthetic potential of the obtained
Inverse Electron-Demand Aza-Diels–Alder Reaction of α,β-Unsaturated Thioesters with In Situ-Generated 1,2-Diaza-1,3-dienes for the Synthesis of 1,3,4-Thiadiazines
electron-demand aza-Diels–Alder reaction of α,β-unsaturated thioesters with 1,2-diaza-1,3-dienes generated in situ from α-halogeno hydrazones was developed. With α,β-unsaturated thioesters as C═S dienophiles, the developed protocol enables the formation of diverse 3,6-dihydro-2H-1,3,4-thiadiazine derivatives in excellent yields. In the presence of lithiumaluminumhydride, 3,6-dihydro-2H-1,3,4-thiadiazine
开发了α,β-不饱和硫酯与 α-卤代腙原位生成的 1,2-二氮杂-1,3-二烯的高度区域选择性逆电子需求氮杂-狄尔斯-阿尔德反应。以 α,β-不饱和硫酯作为 C=S 亲双烯体,所开发的方案能够以优异的收率形成多种 3,6-二氢-2 H -1,3,4-噻二嗪衍生物。在氢化铝锂的存在下,3,6-二氢-2 H -1,3,4-噻二嗪衍生物可以进一步转化为5,6-二氢-4 H -1,3,4-噻二嗪,收率良好。