通过使用二氯苯醌促进的无环1,5-烯醇和1,5-二炔醇的氧化环芳构化反应,描述了发散的苯并[ b ]芴酮的简便高效合成方法。这些级联反应的成功取决于初始Meyer-Schuster重排产生烯丙醇中间体的化学选择性,随后是区域选择性的Schmittel环化反应,以及随后的Friedal-Crafts烷基化反应或末端Ar部分的自由基进攻。反应中仅需要氧化剂和溶剂,因此在不含金属的条件下提供了一个小的库,具有所需的具有优异的官能团耐受性的预期多碳环产物。选定的苯并[ b]的吸收和光致发光特性还研究了芴酮。结果表明,在苯基部分包含给电子体4-OMe基团的化合物(2h)显示出深绿色发射光(491nm)。
An elegant Lewisacidcatalyzed, protection-free, and straightforward synthetic strategy for the assembly of a series of sophisticated polycyclic quinoline skeletons employing propargylic alcohols and 2-vinylanilines as the substrates in the presence of Yb(OTf)3 (10 mol %) and AgOTf (10 mol %) in tetrahydrofuran has been described. This annulation protocol, which proceeds through a sequential Meyer–Schuster
Tandem reaction of propargyl alcohols and N-tosyl hydroxylamine: switchable synthesis of 2,5-dihydroisoxazoles and 4-halo-2,5-dihydroisoxazoles
作者:Yuanxun Zhu、Guangwei Yin、Lang Sun、Ping Lu、Yanguang Wang
DOI:10.1016/j.tet.2012.09.092
日期:2012.12
2,5-Dihydroisoxazoles, 4-iodo-2,5-dihydroisoxazoles, and 4-bromo-2,5-dihydroisoxazoles were efficiently constructed from propargylic alcohols and N-tosyl hydroxylamine using ytterbium triflate, iodine and N-bromosuccinimide, respectively. N-sulfonylallenamide is postulated to be the key intermediate for these tandem transformations. Moreover, the resulting 4-iodo-2,5-dihydroisoxazoles could be elaborated by palladium-catalyzed carbonylation to generate 4-methoxycarbonyl-4,5-dihydroisoxazoles. (C) 2012 Elsevier Ltd. All rights reserved.