Tuning carbanion reactivity by complexing with boranes: γ‐elimination reaction as a model
作者:Uri Habusha、Esther Rozental、Shmaryahu Hoz
DOI:10.1002/poc.814
日期:2004.11
γ-elimination reactions [Eqn (1)]. With highly acidic alcohols such as trifluoroethanol the protonation is diffusion controlled and the rate for the cross ring elimination reaction is greater by a factor of three (at an alcohol concentration of 1 M). However, in the presence of BH3 or Bu3B, the protonated product becomes dominant. This result is attributed to the binding of the carbanion by the boranes. Experimental
Could Ionic γ-Elimination Be Concerted: Clocking the Internal Displacement Across a Cyclobutane Ring
作者:Uri Habusha、Esther Rozental、Shmaryahu Hoz
DOI:10.1021/ja028644p
日期:2002.12.1
levels off for the two most acidic alcohols, TFE and HFIP which react at a diffusion-controlled rate. The partitioning of the products between protonation and elimination enables, therefore, the determination of the rate constant for the internal elimination as approximately 3 x 10(10) s(-1). Ab initio calculations at the B3LYP/6-31G level show that the elimination from a model carbanion (4, eq 4) occurs