An efficient method for the synthesis of 2,3-dichloro-5-substituted (Cl, CF3, alkyl) pyridines starting from the 1:1 adducts of the copper-catalysed addition of chloral or the corresponding 2,2-dichloroaldehydes to acrylonitrile is presented. Proper choice of experimental conditions allows the preparation of in a one-potprocess. Similarly, the CuCl-catalysed reaction of methyl itaconate with several
5-Phenyl-1,2,3,4-tetrachloro-7,7-dimethoxynotbornadiene (II) may be smoothly cleaved along two pathways at 130°. Methyl 5-phenyl-2,3,4-trichlorobenzoate (VI) and methylchloride are obtained on the one hand, on the other hand result 2,3,4,5-tetrachlorobiphenyl (III) and dimethoxycarbene (XI). The latter may be trapped with methanol yielding methyl ortho-formate or with sulfur giving methyl thionocarbonate
High pressure promoted (2+2) cycloadditions of ketene acetals with carbonyl compounds
作者:René W.M. Aben、Hans W. Scheeren
DOI:10.1016/s0040-4039(00)85970-5
日期:1983.1
Cycloadditions of ketene acetals (R1R2C=C(OR)2) with carbonylcompounds (R3COR4) are strongly promoted by increase or pressure. At 12 kbar oxetanes are even obtained from very polar ketene acetals (R1,R2=H,H or H,Cl) and - in the presence of a Lewis acid - with unactivated ketones (R3 and R4 = alkyl). The reaction proceeds via a cisoid dipolar transition state; when relevant mainly trans-substituted
通过增加或加压,可大大促进乙烯酮缩醛(R 1 R 2 C = C(OR)2)与羰基化合物(R 3 COR 4)的环加成反应。在12kbar下,甚至从极极性的乙烯酮缩醛(R 1,R 2= H,H或H,Cl)和在路易斯酸存在下由未活化的酮(R 3和R 4=烷基)获得氧杂环丁烷。该反应通过一个cisoid偶极过渡态进行。当相关时,主要形成反式取代的氧杂环丁烷。
Negative activation energies for carbene additions to tetramethoxyethylene
作者:Lei Wang、Robert A. Moss、Karsten Krogh-Jespersen
DOI:10.1016/j.tetlet.2016.08.001
日期:2016.9
Activationenergies were determined for the additions of three arylhalocarbenes to tetramethoxyethylene (TMeOE) and tetramethylethylene (TME) in pentane and decane. For addition of 3,5-dinitrophenylchlorocarbene to TMeOE in decane, Ea = −10.4 ± 0.7 kcal/mol, the most negative activationenergy yet encountered in a carbene–alkene addition reaction. Computational studies parallel and elucidate the experimental
确定了在戊烷和癸烷中向四甲氧基乙烯(TMeOE)和四甲基乙烯(TME)中添加三种芳基卤代卡宾的活化能。对于在癸烷中的TMeOE中添加3,5-二硝基苯基氯卡宾,E a = -10.4±0.7 kcal / mol,这是卡宾-烯烃加成反应中遇到的最负的活化能。计算研究平行并阐明了实验结果。