Philkhana Satish Chandra, Malone Joshua A, Armendariz-Gonzalez Estefania, Saputra Adi, Stepherson Jacob R, Fronczek Frank R, Kartika Rendy
Department of Chemistry, 232 Choppin Hall, Louisiana State University, Baton Rouge, LA 70803, USA.
Tetrahedron. 2025 Feb 15;172. doi: 10.1016/j.tet.2024.134415. Epub 2024 Dec 12.
We report the synthesis of -quaternary centers at the α-positions of cyclohexanones. In this chemistry, ionization of an α-hydroxy allyl vinyl ether with Cu(MeCN)4BF4 catalyst at room temperature formed an allyloxy allyl cation that was captured by indole in a regioselective manner to create an α-quaternary center. Upon heating, the Claisen rearrangement occurred to produce a second quaternary center at the opposing α'-position, thereby furnishing the targeted -quaternary center motif. Studies in this article examined the alkyl substituents at the α-carbon and their effect on diastereoselectivity of the Claisen rearrangement. Interestingly, the copper catalyst enhanced the delivery of the allyl group with respect to the indole versus the background diastereoselectivity of the uncatalyzed reaction.
我们报道了在环己酮α-位构建α-季碳中心的合成方法。在此化学过程中，α-羟基烯丙基乙烯基醚在室温下用Cu(MeCN)₄BF₄催化剂进行离子化反应，生成烯丙氧基烯丙基阳离子，该阳离子被吲哚以区域选择性方式捕获，从而形成一个α-季碳中心。加热后，发生克莱森重排反应，在相对的α'-位生成第二个季碳中心，进而得到目标α-季碳中心结构单元。本文的研究考察了α-碳上的烷基取代基及其对克莱森重排非对映选择性的影响。有趣的是，相对于未催化反应的背景非对映选择性，铜催化剂提高了烯丙基相对于吲哚的转移效率。
