Esters of 4-R-4,5-dihydro-1H-pyrazole-3,5,5-tricarboxylic acids with chlorine yield esters of 4-R-5-chloro-4,5-dihydro-3H-pyrazole-3,3,5-tricarboxylic acids that at thermolysis provide the esters of the corresponding 2-chlorocyclopropanetricarboxylic acid. The same esters react with bromine in dichloromethane at room temperature to give a mixture of esters of the corresponding 1H-pyrazole-3,5-dicarboxylic acids and 5-bromo-4,5-dihydro-3,3,5-tricarboxylic acids. From 5,5-diethyl 3-methyl 4,5-dihydro-1H-pyrazole-3,5,5-tricarboxylate and N-iodosuccinimide or a system iodine-silver trifluoroacetate we obtained 1,1-diethyl 2-methyl 2-iodocyclopropane-1,1,2-tricarboxylate.
The intermolecular C–C, C–O, C–S and C–N bonds construction between diazo compounds and acyclic, cyclic 1,3-dicarbonyl compounds, thiophenol, alkynes were developed by using a TFMSA@SBA-15, providing a metal-free and eco-friendly platform.
[3 + 2] cycloaddition and subsequent oxidative dehydrogenation between alkenes and diazo compounds: a simple and direct approach to pyrazoles using TBAI/TBHP
作者:Ying Shao、Jingjing Tong、Yanwei Zhao、Hao Zheng、Liang Ma、Meihua Ma、Xiaobing Wan
DOI:10.1039/c6ob01522k
日期:——
sequential [3 + 2] cycloaddition and oxidative dehydrogenation reactions using TBHP as the primary oxidant. In comparison with previous cases toward pyrazoles from alkenes and diazocompounds, alkenes without a pre-organized leaving group were applied in this transformation. In addition, this methodology was distinguished by its broad substrate scope, commercially available inexpensive starting materials
Novel 1,3-dipolar cycloaddition of diazocarbonyl compounds to alkynes catalyzed by InCl3 in water
作者:Nan Jiang、Chao-Jun Li
DOI:10.1039/b311763d
日期:——
The first intermolecular 1,3-dipolar cycloaddition of diazocarbonylcompounds with alkynes was developed by using an InCl(3) catalyzed cycloaddition in water. The reaction was found to proceed by a domino 1,3-dipolar cycloaddition-hydrogen (alkyl or aryl) migration.
Zeolite NaY promotes 1,3-dipolar cycloaddition of ethyl diazoacetate to alkynes having an electron-withdrawing group to afford the corresponding functionalized pyrazoles in high yields. The activation of the dipolarophile inside the pores of NaY is proposed based on the 13C MAS NMR analysis.
沸石NaY促进了乙基二氮乙酸酯与具有电子吸引基团的炔烃的1,3-偶极环加成反应,从而高产率地获得相应的功能化吡唑。基于13C MAS NMR分析,提出了活化偶极亲和体在NaY微孔内进行的机制。