有機催化不對稱 Oxa-麥可/麥可環化加成連鎖反應:多取代苯併二氫吡喃衍生物的製備

Abstract

單一操作，有機不對稱催化連鎖反應，已成為強而有力的合成方法，可構建 多個碳-碳鍵和化學立體中心。此類型反應對不對稱催化領域發展有很大進步， 大多數反應需要金屬催化劑或嚴格的反應條件。在有機合成中，親核試劑添加至 溴基硝基烯烴為重要的麥可加成反應，因為它們具有多重反應性和產生具有有價 值的分子架構。在此研究中，我們發展了新穎合成方法，以雙成份兩步驟合成含有鹵化四級 碳立體中心的色烷衍生物，以雙官能基之方醯胺不對稱催化劑，經由有機不對稱 催化 oxa-麥可/麥可環化連鎖反應，獲得了預期的產物，其具有良好的化學產率 (22 -89 %)和鏡像超越值(31-97 % ee)。

Organocatalytic asymmetric cascade reactions have become a powerful synthetic paradigm for the construction of multiple carbon–carbon and stereogenic centers in a single operation. Although the catalytic asymmetric reactions were well developed, most of them required metal catalysts or the harsh reaction condition. One of the important Michael addition reactions is the addition of nucleophiles to bromonitroalkene due to their multiple reactivities and the valuable synthetic building blocks that are created.In this research, we reported a new method for the two-component, two-step synthesis of chromane derivatives containing halogenated quaternary carbon stereocenter via an organocatalytic asymmetric cascade oxa-Michael/Michael cyclization sequence using a bifunctional squaramide catalyst. The desired products were obtained in 22 -89% yield and 31-91% ee.