Migratory Decarboxylative Coupling of Coumarins: Synthetic and Mechanistic Aspects
作者:Ranjan Jana、James J. Partridge、Jon A. Tunge
DOI:10.1002/anie.201100765
日期:2011.5.23
On the move: Decarboxylative coupling of allyl 4‐methyl‐3‐carboxycoumarins provides the products of γ‐allylation of the methyl group rather than the typical regiospecific α‐allylation. Mechanistic studies show that intramolecular proton transfer from the 4‐methyl group to the 3‐carboxylate allows allylation of the remote methyl group. The resulting 4‐butenyl‐3‐carboxyl coumarin undergoes Pd0‐catalyzed
进展:烯丙基 4-甲基-3-羧基香豆素的脱羧偶联提供了甲基 γ-烯丙基化的产物,而不是典型的区域特异性 α-烯丙基化。机理研究表明,分子内质子从 4-甲基转移到 3-羧酸酯可以实现远程甲基的烯丙基化。所得的 4-丁烯基-3-羧基香豆素经过 Pd 0催化脱羧,得到观察到的产物(参见方案)。