作者:Hirotaka Sasaki、Kotaro Kiyotaki、Ayumi Imayoshi、Kazunori Tsubaki
DOI:10.1248/cpb.c19-01117
日期:2020.4.1
Various aromatic lactones have been synthesized and their regioselectivity (1,2-addition vs. 1,4- or 1,6-addition) investigated in reactions with organolithium species, particularly n-BuLi and sec-BuLi. The regioselectivity varied greatly depending on various factors, such as the bulkiness of both substrates and organolithium species, and types of solvent and cosolvent. In particular, 1,4-addition with dearomatization occurred preferentially using sec-BuLi as the nucleophile in tetrahydrofuran (THF) with hexamethylphosphoramide (HMPA) or N,N′-dimethylpropyleneurea (DMPU) as cosolvent. For sec-BuLi, the reaction was estimated to proceed through a single-electron transfer mechanism.
我们合成了各种芳香族内酯,并研究了它们在与有机锂(尤其是正-BuLi 和仲-BuLi)反应时的区域选择性(1,2-加成与 1,4- 或 1,6- 加成)。反应的区域选择性因各种因素(如底物和有机锂的体积、溶剂和助溶剂的类型)的不同而有很大差异。特别是,在以六甲基磷酰胺(HMPA)或 N,N′-二甲基丙烯脲(DMPU)为共溶剂的四氢呋喃(THF)中,以仲丁锂为亲核体的 1,4-加成脱芳香化反应优先发生。对于仲丁基锂,估计反应是通过单电子转移机制进行的。