Fast tin-free hydrodehalogenation and reductive radical cyclization reactions: a new reduction process.
Fast tin-free hydrodehalogenation and reductive radical cyclization reactions: a new reduction process.
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快速无锡加氢脱卤和还原自由基环化反应：一种新的还原工艺。
DOI：
10.1002/chin.200431050
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发表时间：
2004
影响因子：
3.6
通讯作者：
R. Rossi
中科院分区：
文献类型：
--
作者：
Santiago E. Vaillard;A. Postigo;R. Rossi
几种芳基、烷基氯化物和溴化物与还原苯甲酸乙酯5H单阴离子进行光刺激反应，得到了高收率的还原产物。如果芳基部分具有合适的双键，则可以得到高收率的环化还原产物。1-烯丙氧基-2-溴苯（1a）与5H的光刺激反应生成3-甲基-2,3-二氢苯并呋喃（2a），产率为97%。当使用1-烯丙氧基-2-氯苯（1b）时，2a的产率仅为55%，当在反应混合物中加入丙酮烯醇酸离子作为夹带剂时，2a的产率可达91%。用二烯丙基-（2-溴苯基）胺（3a）和2-烯丙基-1-卤代萘（氯，4b和溴，4a）得到的环化还原产物收率在96%以上。通过竞争实验，5H与1-萘基自由基的反应速度是苯硫代酸盐离子的5倍左右，接近扩散极限速率。
The photostimulated reactions of several aryl and alkyl chlorides and bromides with the monoanion of reduced ethyl benzoate 5H furnish the reduced products in high yields. If the aryl moieties have suitable double bonds, the cyclized reduced products are obtained in high yields. The photostimulated reaction of 1-allyloxy-2-bromobenzene (1a) with 5H affords 3-methyl-2,3-dihydro-benzofuran (2a) in 97% yield. When 1-allyloxy-2-chlorobenzene (1b) is used, the yield of 2a is only 55%, which increases up to 91% when acetone enolate ion is added to the reaction mixture as entrainment reagent. With diallyl-(2-bromophenyl)amine (3a), and 2-allyloxy-1-halonaphthalenes (chloro, 4b, and bromo, 4a) the cyclized reduced products are obtained in yields above 96%. By competition experiments, 5H reacts ca. 5 times faster with 1-naphthyl radicals than benzenethiolate ions do, which is near the diffusion limit rate.