Abstract A route to 3-benzylidene-dihydrofurochromen-2-ones from 2H-chromenes is described. Lactonization of 2H-chromenes was achieved using a two-step cyclopropanation-rearrangement sequence. Subsequent conversion of these intermediates to the corresponding α-benzylidene lactones was achieved by lithium enolate aldol reaction, followed by base-promoted elimination of the aldolate mesylates. The alkene geometry was found to be base-dependent. While the use of KOBut favored formation of the E isomer, the application of DBU showed a slight preference for the Z isomer. In further studies, these 3-benzylidene-dihydrofurochromen-2-ones were converted to polyaromatic structures possessing all the required functionality for biflavonoid synthesis.

中文翻译：

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3-benzylidene-dihydrofurochromen-2-ones 的合成：双黄酮合成的有前途的中间体

摘要 描述了从 2H-色烯到 3-亚苄基-二氢呋喃-2-酮的路线。2H-色烯的内酯化是使用两步环丙烷化重排序列实现的。随后这些中间体转化为相应的 α-亚苄基内酯是通过烯醇锂醛醇反应实现的，然后是碱促进的甲磺酸醛醇酯消除。发现烯烃几何形状与碱有关。虽然使用 KOBut 有利于形成 E 异构体，但 DBU 的应用显示出对 Z 异构体的轻微偏好。在进一步的研究中，这些 3-benzylidene-dihydrofurochromen-2-ones 被转化为多芳烃结构，具有双黄酮合成所需的所有功能。