of in situ generated arynes with vinyl sulfides provides benzannulated sulfonium ylides in a (3+2) cycloaddition. Trapping of the intermediate ylides with electrophiles (proton transfer or a second aryne addition) and subsequent β‐elimination give rise to di‐, tri‐, or tetrasubstituted alkenes with high stereoselectivity. Experimental studies and DFT calculations provide insight into the mechanisms of
assembly of benzo[c]carbazole derivatives via the Diels–Alder reaction of arynes and easily accessible 2-alkenylidoles was reported. By employing different aryne precursor loads, 6,7-dihydrobenzo[c]carbazoles or aryl-substituted 7,11b-dihydrobenzo[c]carbazoles could be controllably generated in good to excellent yields under a nitrogen atmosphere. On the other hand, when the reaction was conducted under
据报道,苯并[ c ]咔唑衍生物可通过芳烃和易于接近的2-烯基基团的狄尔斯-阿尔德反应直接组装。通过使用不同的芳烃前体负载量,可以在氮气氛下以良好至优异的产率可控制地生成6,7-二氢苯并[ c ]咔唑或芳基取代的7,11b-二氢苯并[ c ]咔唑。另一方面,当反应在氧气下进行时,可以一步一步地以高选择性和高效率直接生成氧化/芳构化产物苯并[ c ]咔唑。有趣的是,苯并[ c上述产物的]咔唑-5-羧酰胺酰胺化衍生物显示出良好的抗肿瘤活性。还描述了这些分子对癌细胞的抑制作用。
Steric Effects Compete with Aryne Distortion To Control Regioselectivities of Nucleophilic Additions to 3-Silylarynes
作者:Sarah M. Bronner、Joel L. Mackey、K. N. Houk、Neil K. Garg
DOI:10.1021/ja306723r
日期:2012.8.29
We report an experimental and computational study of 3-silylarynes. The addition of nucleophiles yield ortho-substituted products as a result of aryne distortion, but meta-substituted products form predominately when the nucleophile is large. Computations correctly predict the preferred site of attack observed in both nucleophilic addition and cycloaddition experiments. Nucleophilic additions to 3-tert-butylbenzyne, which is not significantly distorted, give meta-substituted products.