經由有機催化1,6-/縮醛化/1,4-連鎖反應合成三環苯併二氫吡喃之架構

Abstract

本文藉著使有具有拉電子基共軛雙烯化合物，及具有多反應位點之1-(2'-羥基苯基)丁烷-1,3-二酮，透過有機鹼活化下，進行1,6-/acetalization/1,4-加成連鎖反應，建立三環苯併二氫吡喃架構，且具有五個立體中心的產物，但其非鏡像選擇性不佳（1.6:1 dr）；爾後，添加丁烯酮作為親電子性試劑，再進行1,4-加成反應，可使提升非鏡像選擇性（9:1 dr），有不錯的產率高達89%，且包含兩個四級碳的立體化學中心。此反應也可以進行一鍋化反應，利用雙烯、1-(2'-羥基苯基)丁烷-1,3-二酮及丁烯酮進行一鍋化1,6-/acetalization/1,4-/1,4-加成連鎖反應，也可以有好的產率74%，以及維持其非鏡像選擇性（9:1 dr）。然而，具有鏡像選擇性之產物，仍在進行探討研究中。

An organic base catalyzed 1,6-/acetalization/1,4- cascade reaction between 1-(2'-hydroxyphenyl)butane-1,3-dione with many reactive sites and conjugated dien with strong electron withdrawing group leads to the formation of synthetically important tricyclic chromanes scaffolds bearing five stereogenic centers. However, the diastereoselectivities not well（1.6:1 dr）. After that, with methyl vinyl ketone as electrophile reagent to 1,4-addition can improving diastereoselectivities（9:1 dr）in good yield（89%）and including two tetrasubstituted carbon stereogenic centers. This reaction was also put into the process of one pot directly from conjugated dien, 1-(2'-hydroxyphenyl)butane-1,3-dione and methyl vinyl ketone through efficient 1,6-/acetalization/1,4-/1,4- cascade reaction in well yield（74%）and maintain the diastereoselectivities（9:1 dr）. Nevertheless, the enantioselectivity of product is still in study.