Experimental and Theoretical Study of Tunable 1,3-Lithium Shift of Propargylic/Allenylic Species, Transmetallation, and Pd-Catalyzed Cross-Coupling Reactions
作者:Jinbo Zhao、Yu Liu、Qiwen He、Yuxue Li、Shengming Ma
DOI:10.1002/chem.200900325
日期:2009.10.26
transmetallation and Pd‐catalyzed Negishi coupling reactions afforded 1,1‐diaryl or 1,3‐diaryl allenes with high selectivity. Deuterium‐labeling cross experiments indicated that an intermolecular lithiation process occurred in both 1,3‐lithium shift conditions (conditions B and D). 1‐Arylalka‐1,2‐diene was confirmed experimentally to be the intermediate. A computational study at the B3LYP level for the isomerization
在1-芳基烷基-1-炔的去质子化反应中,实现了从1-芳基烷基1,2-二烯-1-基锂到1-芳基烷基1,2-dien-3-基锂的异构化的高度选择性调节(条件A和B)和1-芳基丁3烯-1-炔与烷基锂的碳环化反应(条件C和D)。随后的金属转移和Pd催化的Negishi偶联反应提供了具有高选择性的1,1-二芳基或1,3-二芳基异戊烯。氘标记的交叉实验表明,分子间锂化过程发生在两种1,3-锂转移条件下(条件B和D)。实验证明1-芳基1,2-二烯是中间体。在B3LYP级别进行异构化的计算研究表明,在3位H的酸度比在1苯基1,2-丁二烯1位的H的酸度高。在条件B下,我镨2 NH作为质子载体完成1,3-锂移。在溶剂化模型中确定速率的步骤的总活化势垒为≈21.0kcal mol -1,这表明异构化在室温下是合理的。对于在条件D下的异构化,DFT计算表明添加TMEDA(四甲基乙二胺)和HMPA(六甲基磷酰胺)会