Analysis of an Asymmetric Addition with a 2:1 Mixed Lithium Amide/<i>n</i>-Butyllithium Aggregate
作者:Jia Liu、Deyu Li、Chengzao Sun、Paul G. Williard
DOI:10.1021/jo800592d
日期:2008.6.1
A 2:1 lithium amide/n-butyllithium aggregate 1 is investigated as an asymmetric addition template in hydrocarbon solvents. Several different chiral lithium amides were synthesized from l-valine and tested in the asymmetric addition of n-BuLi to various aldehydes. Enantiomeric excesses up to 83% were obtained in the case of the addition of n-BuLi to pivaldehyde at −116 °C in pentane. 1H and 13C INEPT
研究了2:1的氨基锂/正丁基锂聚集体1作为烃类溶剂中的不对称加成模板。从1-缬氨酸合成了几种不同的手性锂酰胺,并在将n -BuLi不对称加成到各种醛中进行了测试。在戊烷中,在-116°C下将正丁基锂添加到四乙醛中时,对映体过量高达83%。1 H和13 C INEPT DOSY用于表征新的三聚体复合物122当量的酰胺锂和1当量的醇锂之间。这种混合的聚集体强烈表明了产物诱导的手性抑制的可能性,这不利于不对称加成反应的对映选择性。
Copper-Catalyzed Rearrangement of Tertiary Amines through Oxidation of Aliphatic CH Bonds in Air or Oxygen: Direct Synthesis of α-Amino Acetals
作者:Jie-Sheng Tian、Teck-Peng Loh
DOI:10.1002/anie.201003646
日期:2010.11.2
A surprising turn of events: Mechanistic studies, including trapping, control, and isotope‐labeling experiments, led to the proposal of a rearrangement mechanism involving oxidation of aliphatic CH bonds (see scheme; TMEDA=tetramethylethylenediamine).