Liu Yuefei, Liu Qian, Liu Rongfang, Liu Xiaoqi, Guo Hongyu, Yang Wenjing, Zhou Rong
College of Chemistry, Taiyuan University of Technology, Taiyuan 030024, P. R. China.
College of Traditional Chinese Medicine and Food Engineering, Shanxi University of Chinese Medicine, Jinzhong 030619, P. R. China.
Org Lett. 2024 Sep 20;26(37):7902-7907. doi: 10.1021/acs.orglett.4c02824. Epub 2024 Sep 9.
Herein, we report an unprecedented P(NMe)-mediated reductive insertion of 1,2-dicarbonyl compounds including α-keto esters and isatins into phthalic anhydride-derived alkenes and phthalic anhydrides, which furnishes the corresponding isochroman-1-ones and isochroman-1,4-diones, respectively, in moderate to excellent yields with high chemo- and regioselectivity. Furthermore, the asymmetric version of the ring expansion reaction could be realized by using a chiral auxiliary strategy. Mechanistically, the nucleophilic attack of the Kukhtin-Ramirez adduct, generated from P(NMe) and 1,2-dicarbonyl compound, to the anhydride derivative, followed by a cascade ring-opening and ring-closure process, affords the ring expansion product. The reaction represents a novel metal-free carbon insertion ring expansion of aliphatic rings and also the first [1 + 5] annulation involving the Kukhtin-Ramirez adducts.
在此，我们报道了一种前所未有的由P(NMe)介导的1,2 - 二羰基化合物（包括α - 酮酯和异吲哚酮）向邻苯二甲酸酐衍生的烯烃和邻苯二甲酸酐的还原插入反应，该反应分别以中等至优异的产率以及高化学和区域选择性得到相应的异苯并二氢吡喃 - 1 - 酮和异苯并二氢吡喃 - 1,4 - 二酮。此外，通过使用手性辅助策略可以实现环扩展反应的不对称版本。从机理上讲，由P(NMe)和1,2 - 二羰基化合物生成的库克廷 - 拉米雷斯加合物对酸酐衍生物的亲核攻击，随后是级联的开环和闭环过程，得到环扩展产物。该反应代表了一种新型的无金属脂肪族环碳插入环扩展反应，也是涉及库克廷 - 拉米雷斯加合物的首例[1 + 5]环化反应。
