Arenediazonium o-benzenedisulfonimides can be used as new and efficient reagents for Heck-type arylation reactions of some common substrates containing C–C multiple bonds, namely ethyl acrylate, acrylic acid, acroleyne, styrene and cyclopentene. The reactions were carried out in an organic solvent, in the presence of Pd(OAc)2 as pre-catalyst, and gave rise to arylated products, for example, ethyl cinnamates
Alkyl- and Arylthiodediazoniations of Dry Arenediazonium <i>o</i>-Benzenedisulfonimides. Efficient and Safe Modifications of the Stadler and Ziegler Reactions to Prepare Alkyl Aryl and Diaryl Sulfides
yields were obtained only when sterically hindered diazoniumsalts or thiols were used. A good amount of the o-benzenedisulfonimide (8) was always recovered from the reactions and could be reused to prepare salts 1. The copious experimental data collected in homogeneous conditions have offered several starting points for the study of the mechanism of these reactions.
Aryl methanesulfonates 3 (18 examples) were easily prepared by thermal decomposition of dry arenediazonium o-benzene-disulfonimides 1 in methanesulfonic acid (2). The reactions were carried out at temperatures between 60 and 120 °C for times between 0.5 and 8 h. The aryl methanesulfonates were obtained in reproducible yield of 70-90%, with few exceptions. In all cases the o-benzenedisulfonimide (4) could be recovered in good yields which can then be reused to prepare the salts 1. When thermal decomposition of salts 1 was carried out in trifluoromethanesulfonic acid (5) at 90-120 °C for 1-2 h, aryl trifluoromethanesulfonates 6 were obtained in 73-78% yield (3 examples).
suggesting a hindered rotation around the C2–N bond, of which a double bond character was also evidenced by X-ray diffraction analyses. The free energies of activation for the rotational processes have been obtained from 1H NMR experiments and computer simulations at different temperatures and provided good correlation with the σ constants of the substituents on the ‘remote’ benzene ring. This represents
通过2- N-吡咯烷基二噻唑与一系列主要在对位带有电子效应不同的基团的芳基重氮盐的反应,在温和的条件下以高收率获得了新的5-偶氮取代的噻唑衍生物。产物的NMR谱图显示了在α位上的亚甲基向吡咯烷基氮的广泛信号,这表明绕C2-N键的旋转受阻,X射线衍射分析也证明了其双键特性。通过1 H NMR实验和计算机模拟在不同温度下获得了旋转过程的活化自由能,并提供了与σ的良好相关性“远程”苯环上取代基的常数。这表示出乎意料且特殊的结果,因为已证明绕C2-N键的旋转受限是受非常远的取代基影响的。2,4-二-N-吡咯烷基基噻唑与2- N-吡咯烷基基噻唑在芳基重氮盐中的反应性强得多。