Chiral N-Heterocyclic Carbene鈭扖opper(I)-Catalyzed Asymmetric Allylic Arylation of Aliphatic Allylic Bromides: Steric and Electronic Effects on 纬-Selectivity

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• 作者：Khalid B. Selim ; Hirotsugu Nakanishi ; Yasumasa Matsumoto ; Yasutomo Yamamoto ; Ken-ichi Yamada ; Kiyoshi Tomioka
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：March 4, 2011
• 年：2011
• 卷：76
• 期：5
• 页码：1398-1408
• 全文大小：930K
• 年卷期：v.76,no.5(March 4, 2011)
• ISSN：1520-6904

文摘

Chiral N-heterocyclic carbene ligands were electronically and sterically tuned to improve 纬-selectivity in copper(I)-catalyzed asymmetric allylic arylation of aliphatic allylic bromides with several aryl Grignard reagents. High 纬-selectivity was realized when either the aryl group of the Grignard reagent or the aryl group on the N-substituent of the carbene ligand was electron-deficient or when either the carbene ligand or allylic bromide was bulky. The results indicated that electron deficiency and steric hindrance of the initially formed 蟽-allyl copper intermediate enhance the rate of the reductive elimination to give 纬-products as major isomers.