Synthesis of Siloxy-α-Lapachone Derivatives by Chemo- and Regioselective Diels-Alder Reactions of 3-Methylene-1,2,4-naphthotriones with Silyl Enol Ethers
作者:Jian-Hua Xu、Da-Quan Peng、Yun Liu、Zhi-Feng Lu、Yong-Miao Shen
DOI:10.1055/s-2008-1042950
日期:2008.4
2-hydroxy-1,4-naphthoquinone with aliphatic and aromatic aldehydes, take part in chemoselective hetero-Diels-Alder reactions with silyl enol ethers to give a series of siloxy-containing naphtho[2,3- B]pyran-5,10-dione (α-lapachone) derivatives in moderate to high yield. These reactions regio-selectively gave α-lapachone derivatives with an acetal structure. This regioselectivity can be rationalized by
O-醌甲基化物,由 2-羟基-1,4-萘醌与脂肪族和芳香族醛的 Knoevenagel 缩合原位生成,与甲硅烷基烯醇醚参与化学选择性杂-Diels-Alder 反应,得到一系列含甲硅烷氧基的化合物萘并[2,3- B]吡喃-5,10-二酮(α-拉帕酮)衍生物,产率中等至高。这些反应区域选择性地产生具有缩醛结构的α-拉帕酮衍生物。这种区域选择性可以通过考虑邻醌甲基化物与甲硅烷基烯醇醚的前沿分子轨道相互作用来合理化,并考虑到能量上更有利的途径导致迈克尔加成中低能量的两性离子状过渡态两种反应物。