Ligand Effects in the Formation of Tertiary Carbanions from Substituted Tertiary Aromatic Amides
作者:Alison Campbell Smith、Morgan Donnard、Joanna Haywood、Mary McPartlin、Mark A. Vincent、Ian H. Hillier、Jonathan Clayden、Andrew E. H. Wheatley
DOI:10.1002/chem.201100240
日期:2011.7.11
in solution. In line with this, the same (benzylic) deprotonation is noted if the reaction is attempted in the presence of tridentate diglyme, with X‐ray crystallography revealing that the metal is now closer to the tertiary carbanion (2.497(4) Å). Electrophilic quenches of lithiated 5 have allowed, for the first time, the formation of quaternary benzylic substituents by lateral lithiation.
2-异丙基的反应(Ñ,Ñ二异丙基) -苯甲酰胺5与吨BuLi的乙醚中结果邻 去质子化和半溶剂化物的基础上(一个四核二聚体形成5 -Li ö)2 ⋅Et 2 O的固态结构具有二聚体核,其中酰胺氧原子无法稳定金属离子,但可用于与位于核外围的两个金属化单体相互作用。的反应5与吨BuLi的三齿路易斯碱PMDTA的存在(Ñ,Ñ,Ñ′,N ′′,N ′′-五甲基二亚乙基三胺)采取不同的过程。尽管叔脂族基团的在2-位5,X射线晶体学揭示了显着的苄基发生(横向)去质子化,得到的叔benzyllithium 5 -Li升⋅PMDTA。固态结构揭示了PMDTA的酰胺配位和溶剂化作用使Li +离子与2- i的去质子化的α-C相隔一定距离Pr基团(3.859(4)Å),因此得到基本上平坦的叔碳负离子和高度扭曲的芳族体系。DFT分析表明,金属离子在溶液中更靠近碳负离子中心。与此相一致,如果在三齿二甘醇二甲醚存在