Palladium-Catalyzed Annulation of Aryl-1,2-diols and Propargylic Carbonates. Theoretical Study of the Observed Regioselectivities
作者:Jean-Robert Labrosse、Paul Lhoste、Françoise Delbecq、Denis Sinou
DOI:10.1002/ejoc.200300071
日期:2003.8
the case of methoxy-substituted diphenol, and a single regioisomer for the nitro- and the formyl-substituted diphenols. The oxyanion which attacks first corresponds to the less acidic hydroxy function, and the attack of the second oxyanion on the η3-allylpalladium intermediate is directed toward the more substituted carbon atom. In order to explain the regioselectivity of the cyclization, a theoretical
1-甲基丙-2-炔基碳酸酯与 3-和 4-取代的苯-1,2-二醇反应得到 2,3-二氢-3-甲基-2-亚甲基-1,4-苯并二恶英的混合物在甲氧基取代的二酚的情况下为区域异构体,对于硝基和甲酰基取代的二酚为单一的区域异构体。首先攻击的氧阴离子对应于酸性较弱的羟基官能团,第二个氧阴离子对 η3-烯丙基钯中间体的攻击指向更多取代的碳原子。为了解释环化的区域选择性,已经进行了基于密度泛函理论(DFT)的理论研究。第一步意味着两个氧阴离子之间的平衡。第二步的区域选择性是由于磷烷的性质、体积、和取代基的电子性质。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)