intramolecular silyl triflate-induced cyclization of an in situ-generated silyl ketene acetal onto an imide carbonyl group (e.g., 7 to 8) was developed. The IMDA relative reactivities of a family of valence bond isomers, each differing in the precise nature of the dienophilic subunit, were determined. Under biologically relevant conditions (D2O, pH 7.2 buffer, ca. 25 degrees C), triene 2, via its lactone ring-opened
完成了结构迷人的真菌代谢物 UCS1025A (1) 的合成。它的特点是通过推定的
三烯前体 (2) 的分子内狄尔斯-阿尔德 (I
MDA) 反应对八烷亚基进行仿生方法,然后在该化合物中有效构建二杂四喹烷亚基。具体而言,开发了分子内甲
硅烷基
三氟甲磺酸酯诱导的原位生成的甲
硅烷基
乙烯酮缩醛环化到
酰亚胺羰基(例如,7至8)上。确定了价键异构体家族的 I
MDA 相对反应性,每个异构体在亲二烯亚基的精确性质上都不同。在
生物学相关条件下(D2O,pH 7.2 缓冲液,约 25 摄氏度),
三烯 2 通过其内酯开环同源物,