Crombie Aimee L, Kane John L, Shea Kevin M, Danheiser Rick L
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
J Org Chem. 2004 Dec 10;69(25):8652-67. doi: 10.1021/jo048698c.
A "ring expansion-annulation strategy" for the synthesis of substituted azulenes is described based on the reaction of beta'-bromo-alpha-diazo ketones with rhodium carboxylates. The key transformation involves an intramolecular Buchner reaction followed by beta-elimination of bromide, tautomerization, and in situ trapping of the resulting 1-hydroxyazulene as a carboxylate or triflate ester. Further synthetic elaboration of the azulenyl halide and sulfonate annulation products can be achieved by employing Heck, Negishi, Stille, and Suzuki coupling reactions. Reaction of the azulenyl triflate 84 with pinacolborane provides access to the azulenylboronate 91, which participates in Suzuki coupling reactions with alkenyl and aryl iodides. The application of these coupling reactions to the synthesis of biazulenes, terazulene 101, and related oligoazulenes is described, as well as the preparation of the azulenyl amino acid derivative 110.
本文描述了一种基于β'-溴-α-重氮酮与羧酸铑反应的合成取代薁类化合物的“扩环-环化策略”。关键转化步骤包括分子内布赫纳反应，随后是溴的β-消除、互变异构，以及将生成的1-羟基薁原位捕获为羧酸盐或三氟甲磺酸盐酯。通过使用赫克反应、根岸反应、施蒂勒反应和铃木反应，可以进一步对薁基卤化物和磺酸盐环化产物进行合成修饰。薁基三氟甲磺酸盐84与频哪醇硼烷反应可得到薁基硼酸酯91，其可与烯基和芳基碘化物发生铃木反应。本文还描述了这些偶联反应在双薁类化合物、三联薁101及相关低聚薁合成中的应用，以及薁基氨基酸衍生物110的制备。
