Toward Novel Antioxidants: Preparation of Dihydrotellurophenes and Selenophenes by Alkyltelluride-Mediated Tandem S<sub>RN</sub>1/S<sub>H</sub>i Reactions<sup>1</sup>
作者:Lars Engman、Melissa J. Laws、Jonas Malmström、Carl H. Schiesser、Lisa M. Zugaro
DOI:10.1021/jo9907235
日期:1999.9.1
distributions similar to those observed for reactions involving n-BuTeNa. Lithium or sodium phenyltellurolate returned only starting materials from these reaction mixtures. The 2-[2-(n-butyltelluro)-1-hydroxy-1-methyl]ethylphenyl radical (14) is estimated to cyclize with k(c) = 5 x 10(8) s(-)(1) at 25 degrees C. The tandem S(RN)1/S(H)i sequence has been applied to the preparation of the antioxidant analogues, 5-hydroxy-2
1-(2-碘苯基)-1-甲基环氧乙烷(12)与2当量的正丁基碲铝酸钠(n-BuTeNa)的反应,是由四氢化二正丁基硼氢化钠在THF中的硼氢化钠还原生成的,得到2, 3-二氢-3-羟基-3-甲基苯并[b] tellurophene(13)的产率为62%,以及少量的1-(n-丁基碲基)-2-苯基-2-丙醇(27)。该转化大概涉及串联的S(RN)1 / S(H)i序列。1-(苄基硒基)-2-苯基-2-丙醇(5a,R = Me)和1-烯丙氧基-2-碘苯(15)的相似反应得到2,3-二氢-3-羟基-3-甲基苯并[b]分别是]硒烯(17,74%)和3-(正丁基碲基)甲基-2,3-二氢苯并[b]呋喃(18,50%)。通过将碲直接插入所需的烷基锂中生成的烷基碲酸锂,碲上的叔丁基或叔丁基或叔丁基取代提供的产物分布与涉及正丁基萘的反应观察到的产物分布相似。苯基碲酸锂或钠仅从这些反应混合物中返回原料。估计2-