摘要/Abstract
手性胺类化合物广泛存在于天然产物、药物分子和多功能材料中, 而且作为重要中间体、催化剂和手性辅剂在有机合成中也有广泛的应用, 因此, 发展高效的方法合成各种手性胺化合物及相应的骨架结构具有重要的科学意义和应用价值. 有机硼试剂、胺和羰基化合物参与的不对称Petasis三组分反应是构建手性胺及其衍生物最简洁、高效的方法之一. 近年来, 利用该策略来构建手性胺类化合物引起了广泛的关注. 文章综述了不对称Petasis反应合成手性胺类化合物的近期研究进展, 主要包括手性胺源、手性羰基化合物和手性硼试剂参与的底物诱导的不对称Petasis反应, 以及手性催化剂促进的不对称Petasis反应, 并对该领域的挑战和未来发展方向进行简要讨论.
关键词: Petasis反应, 手性胺, 硼酸, 不对称合成, 不对称催化
Chiral amines are valuable constituents of many natural products, pharmaceuticals and functional materials, they are also widely utilized as versatile building blocks and important chiral catalysts as well as chiral auxiliaries in organic synthesis. Therefore, it is of great scientific significance and application value to develop efficient methods for the synthesis of structurally diverse chiral amines and chiral amine scaffolds. In 1993, Petasis and co-workers reported an efficient synthesis of allylic amines through a Mannich-type reaction of vinylboronic acids with secondary amines and paraformaldehyde, where the organoboron reagents served as the nucleophilic component. Since then, this three-component Petasis reaction of organoboron reagents with amines and carbonyl derivatives has been developed as an appealing and concise method to access various amines. The asymmetric Petasis reaction provides a facile and efficient route to optically active amines and thus has attracted much attention over the past two decades. In this review, we summarize the recent progress achieved in the synthesis of chiral amines by asymmetric Petasis reaction and provide an overview on the methods applied for stereochemical control. The strategies that have been employed for accessing enantioenriched amines, including various chiral substrate-based diastereoselective induction approaches and several recent developments of enantioselective catalysis. In a large number of asymmetric Petasis reaction cases, good to high levels of stereoselectivities can be achieved relying on the utilization of chiral amine source, chiral carbonyl substrates, and chiral organoboron reagents. In particular, chiral amines such as α-methylbenzylamines and chiral α-hydroxy aldehyde analogues have emerged as a broadly applicable class of substrates for asymmetric Petasis reaction. The most promising advance has been the success of catalytic asymmetric Petasis reaction for enantioselective synthesis of chiral amines in the last few years. Chiral bifunctional thioureas and binaphthols have been demonstrated to be effective organocatalysts. Finally, the perspectives on the relevant challenges and future directions in this field are also discussed.
Key words: Petasis reaction, chiral amine, boronic acid, asymmetric synthesis, asymmetric catalysis
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