Cascade Polycyclization: Exploration of a Convergent Route to Access Various Tricyclic and Tetracyclic Products Related to Sterols

The expedient synthesis of tricyclic and tetracyclic compounds via a cascade polycyclization
methodology is described. Nazarov substrates (II) containing two Michael acceptors and a
cyclohexenone ester (I) underwent cycloaddition followed by intramolecular 1,4-addition to furnish,
in a highly stereoselective manner, tricyclic and tetracyclic products (III). Such compounds are
interesting intermediates for the synthesis of polycyclic natural and unnatural products.

本研究报道了采用串联多环化（cascade polycyclization）方法学实现三环与四环化合物的便捷合成。带有两个迈克尔受体（Michael acceptors）的纳扎罗夫底物（Nazarov substrates，II）与环己烯酮酯（cyclohexenone ester，I）先发生环加成反应，随后进行分子内1,4-加成，以高度立体选择性的方式生成三环及四环产物（III）。此类化合物是合成多环天然产物与非天然产物的重要中间体。