Reductive aminations constitute an important class of reactions widely applied in research laboratories and industries for the synthesis of amines as well as pharmaceuticals, agrochemicals and biomolecules. In particular, catalytic reductive aminations using molecular hydrogen are highly valued and essential for the cost-effective and sustainable production of different kinds of amines and their functionalization. These reactions couple easily accessible carbonyl compounds (aldehydes or ketones) with ammonia, amines or nitro compounds in the presence of suitable catalysts and hydrogen that enable the preparation of linear and branched primary, secondary and tertiary amines including N-methylamines and molecules used in life science applications. In general, amines represent valuable fine and bulk chemicals, which serve as key precursors and central intermediates for the synthesis of advanced chemicals, life science molecules, dyes and polymers. Noteworthily, amine functionalities are present in a large number of pharmaceuticals, agrochemicals and biomolecules, and play vital roles in the function of these active compounds. In general, reductive aminations are challenging processes, especially for the syntheses of primary amines, which often are non-selective and suffer from over-alkylation and reduction of carbonyl compounds to the corresponding alcohols. Hence, the development of suitable catalysts to perform these reactions in a highly efficient and selective manner is crucial and continues to be important and attracts scientific interest. In this regard, both homogeneous and heterogeneous catalysts have successfully been developed for these reactions to access various amines. There is a need for a comprehensive review on catalytic reductive aminations to discuss the potential catalysts used and applicability of this methodology in the preparation of different kinds of amines, which are of commercial, industrial and medicinal importance. Consequently, in this review we discuss catalytic reductive aminations using molecular hydrogen and their applications in the synthesis of functionalized and structurally diverse benzylic, heterocyclic and aliphatic primary, secondary and tertiary amines as well as N-methylamines and more complex drug targets. In addition, mechanisms of reductive aminations including selective formation of desired amine products as well as possible side reactions are emphasized. This review aims at the scientific communities working in the fields of organic synthesis, catalysis, and medicinal and biological chemistry.

中文翻译：

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使用分子氢的催化还原胺化反应，用于合成各种胺。

还原性胺化反应是重要的一类反应，广泛用于研究实验室和工业中，用于合成胺以及药物，农用化学品和生物分子。特别地，使用分子氢的催化还原胺化是非常有价值的，并且对于各种胺的经济有效且可持续的生产及其功能化至关重要。这些反应在合适的催化剂和氢气的存在下，将易于获得的羰基化合物（醛或酮）与氨，胺或硝基化合物偶合，从而可以制备线性和支化的伯，仲和叔胺，包括N-甲胺和用于生命科学应用的分子。通常，胺代表有价值的精细和块状化学品，它们是合成高级化学品，生命科学分子，染料和聚合物的关键前体和主要中间体。值得注意的是，胺官能团存在于许多药物，农用化学品和生物分子中，并且在这些活性化合物的功能中起着至关重要的作用。通常，还原性胺化是具有挑战性的过程，特别是对于伯胺的合成而言，伯胺通常是非选择性的，并且遭受过度烷基化和羰基化合物还原为相应醇的困扰。因此，开发合适的催化剂以高效和选择性地进行这些反应至关重要，并且将继续发挥重要作用并引起科学兴趣。在这方面，均已成功地开发出均相和非均相催化剂用于这些反应以得到各种胺。需要对催化还原性胺化进行全面的综述，以讨论使用潜在的催化剂以及该方法在制备具有商业，工业和医学重要性的各种胺中的适用性。因此，在这篇综述中，我们讨论了使用分子氢的催化还原胺化反应及其在官能化和结构上不同的苄基，杂环和脂肪族伯，仲和叔胺以及 已经成功地开发出均相和非均相催化剂，用于这些反应以得到各种胺。需要对催化还原性胺化进行全面的综述，以讨论使用潜在的催化剂以及该方法在制备具有商业，工业和医学重要性的各种胺中的适用性。因此，在这篇综述中，我们讨论了使用分子氢的催化还原胺化反应及其在官能化和结构上不同的苄基，杂环和脂肪族伯，仲和叔胺以及 已经成功地开发出均相和非均相催化剂，用于这些反应以得到各种胺。需要对催化还原性胺化进行全面的综述，以讨论使用潜在的催化剂以及该方法在制备具有商业，工业和医学重要性的各种胺中的适用性。因此，在这篇综述中，我们讨论了使用分子氢的催化还原胺化反应及其在官能化和结构上不同的苄基，杂环和脂肪族伯，仲和叔胺以及 需要对催化还原性胺化进行全面的综述，以讨论使用潜在的催化剂以及该方法在制备具有商业，工业和医学重要性的各种胺中的适用性。因此，在这篇综述中，我们讨论了使用分子氢的催化还原胺化反应及其在官能化和结构上不同的苄基，杂环和脂肪族伯，仲和叔胺以及 需要对催化还原性胺化进行全面的综述，以讨论使用潜在的催化剂以及该方法在制备具有商业，工业和医学重要性的各种胺中的适用性。因此，在这篇综述中，我们讨论了使用分子氢的催化还原胺化反应及其在官能化和结构上不同的苄基，杂环和脂肪族伯，仲和叔胺以及N-甲胺和更复杂的药物靶标。另外，强调了还原胺化的机理，包括选择性形成所需的胺产物以及可能的副反应。这篇综述针对在有机合成，催化以及药物和生物化学领域中工作的科学界。