A phosphine-promoted tandem Diels–Alderreaction using pentadienyl 4-nitrobenzoate (α-vinyl MBH adduct) as a diene precursor with 3-olefinic oxindoles or CF3-activated ketones as dienophiles has been developed. The reaction proceeds through the formation of a pentadienyl phosphonium intermediate via SN2′′ addition, which acts as both a D–A diene and a precursor for the exomethylene moiety. This method
已经开发出一种膦促进的串联 Diels-Alder 反应,使用 4-硝基苯甲酸戊二烯酯(α-乙烯基 MBH 加合物)作为二烯前体,使用 3-烯基羟吲哚或 CF 3 活化酮作为亲二烯体。该反应通过 S N 2′′ 加成形成戊二烯基鏻中间体,该中间体既充当 D-A 二烯又充当外亚甲基部分的前体。该方法提供了一种无金属且步骤高效的方法来合成带有外亚甲基的螺吲哚和二氢吡喃,它们是天然产物中发现的特殊结构。