C=C双键与分子氧的氧化裂解产生羰基化合物是化学和药物合成中的一个重要转化。在自然界中,含有第一排过渡金属的酶,特别是血红素和非血红素铁依赖性酶,在环境条件下很容易激活 O 2并以极其精确的方式氧化裂解 C=C 键。然而,该反应对合成化学家来说仍然具有挑战性。只有少数已知的合成金属催化剂允许在 O 2大气压下氧化裂解烯烃,很少有人知道催化未活化烯烃的裂解。在这项工作中,我们描述了一种光驱动、Mn 催化的协议,用于在 1 个大气压的 O 2下将烯烃选择性氧化为羰基化合物。首次使用第一排生物相关金属催化剂,在清洁、温和的条件下,可以将芳香族和各种未活化的脂肪族烯烃氧化成酮和醛。此外,该协议显示出非常好的功能组耐受性。机理研究表明,Mn-oxo 物种,包括不对称的混合价双 (μ-oxo)-Mn(III,IV) 络合物,参与氧化,溶剂甲醇参与 O 2活化,导致oxo 物种的形成。
Organocatalytic Asymmetric Reaction Cascade to Substituted Cyclohexylamines
作者:Jian Zhou、Benjamin List
DOI:10.1021/ja072134j
日期:2007.6.1
We report a new strategy for organocatalytic cascade reactions. Accordingly, enamine catalysis, iminium catalysis, and Bronsted acid catalysis can work in concert in a highlyenantioselective organocatalytic cascadesequence toward chiral cis-3-substituted cyclohexylamines. We found that an achiral amine in combination with a catalytic amount of a chiral Bronsted acid can accomplish an aldol additi
Synthesis of <i>trans</i>-3-Substituted Cyclohexylamines via Brønsted Acid Catalyzed and Substrate-Mediated Triple Organocatalytic Cascade Reaction
作者:Benjamin List、Jian Zhou
DOI:10.1055/s-2007-984877
日期:——
We report a new organocatalytic cascade reaction. A combination of the amine substrate with a catalytic amount of a Brønsted acid merges enamine and iminium catalysis with Brønsted acid catalysis in a new organocatalytic cascade reaction. We found that the aniline substrate itself in combination with a catalytic amount of PTSA·H2O can function as an aminocatalyst accomplishing an aldol condensation-conjugate reduction cascade, which terminates in a Brønsted acid catalyzed reductive amination incorporating the amine substrate into the final product. This transformation furnishes trans-3-substituted cyclohexyl amines in good yields and good diastereoselectivities.