Divergent Reactivity of Alkyl Aryl Sulfones with Bases: Selective Functionalization of<i>ortho</i>-Aryl and α-Alkyl Units Enabled by a Unique Carbanion Transmetalation
作者:Lucie Řehová、Ivana Císařová、Ullrich Jahn
DOI:10.1002/ejoc.201301553
日期:2014.3
metalation selectivity of branched alkyl aryl sulfones is described. Such sulfones were found to initially undergo directed ortho-metalation with good regioselectivity, despite having a more acidic α-H atom. The structure of the alkyl unit profoundly, but predictably, influences the regioselectivity of the attack of the base. In β- and γ-branched ortho-(alkylsulfonyl)aryllithiums a transmetalation to the
受电子磺酰基对相邻的 α-H 原子表现出强烈的酸化影响。朱莉娅和相关的烯化就是基于这种效应。这里描述了支链烷基芳基砜金属化选择性的惊人逆转。尽管具有更酸性的 α-H 原子,但发现此类砜最初会以良好的区域选择性进行定向邻位金属化。烷基单元的结构深刻但可预测地影响碱攻击的区域选择性。在 β- 和 γ- 支化的邻(烷基磺酰基)芳基锂中,仅在加热时才会发生向 α-碳负离子的金属转移。然后选择性地应用相应生成的正碳负离子或α-碳负离子,从而允许获得合成有趣的化合物类别。