Generation, Stability, and Utility of Lithium 4,4′-Di-<i>tert</i>-butylbiphenylide (LiDBB)
作者:Richard R. Hill、Scott D. Rychnovsky
DOI:10.1021/acs.joc.6b01748
日期:2016.11.18
Several procedures were evaluated for the preparation of lithium 4,4′-di-tert-butylbiphenylide (LiDBB, Freeman’s reagent) from lithium metal and 4,4′-di-tert-butylbiphenyl (DBB) in THF. Solutions with nominal concentration of 0.4 and 1.0 M were formed. The stability of LiDBB solutions was evaluated over time, and the gradual uptake of lithium metal was observed. At 0 °C the LiDBB solutions were stable
对从金属锂和4,4'-二叔丁基锂制备4,4'-二-叔丁基联苯锂(LiDBB,Freeman试剂)的几种方法进行了评估丁基丁基联苯(DBB)在THF中的溶液。形成标称浓度为0.4和1.0 M的溶液。随时间评估LiDBB溶液的稳定性,并观察到锂金属的逐渐吸收。LiDBB溶液在0°C下在THF中稳定超过一周。LiDBB溶液在20°C时经历了各种分解途径,这导致了更多锂金属的吸收和副产物的积累。研究了这些分解途径,并观察到乙烯在LiDBB破坏THF中的重要性。在实践中,LiDBB的THF溶液在0°C下可稳定保存一周以上,而在-25°C的氩气下保存则可保存37周以上。这些发现将扩展LiDBB在有机合成中作为试剂的用途。