Combinations of Aminocatalysts and Metal Catalysts: A Powerful Cooperative Approach in Selective Organic Synthesis

Abstract

The cooperation and interplay between organic and metal catalyst systems is of utmost importance in nature and chemical synthesis. Here innovative and selective cooperative catalyst systems can be designed by combining two catalysts that complement rather than inhibit one another. This refined strategy can permit chemical transformations unmanageable by either of the catalysts alone. This review summarizes innovations and developments in selective organic synthesis that have used cooperative dual catalysis by combining simple aminocatalysts with metal catalysts. Considerable efforts have been devoted to this fruitful field. This emerging area employs the different activation modes of amine and metal catalysts as a platform to address challenging reactions. Here, aminocatalysis (e.g., enamine activation catalysis, iminium activation catalysis, single occupied molecular orbital (SOMO) activation catalysis, and photoredox activation catalysis) is employed to activate unreactive carbonyl substrates. The transition metal catalyst complements by activating a variety of substrates through a range of interactions (e.g., electrophilic π-allyl complex formation, Lewis acid activation, allenylidene complex formation, photoredox activation, C-H activation, etc.), and thereby novel concepts within catalysis are created. The inclusion of heterogeneous catalysis strategies allows for "green" chemistry development, catalyst recyclability, and the more eco-friendly synthesis of valuable compounds.

Asymmetric one-pot reactions using heterogeneous chemical catalysis: recent steps towards sustainable processes

“…Thus, their application in one-pot reactions also evolved rapidly. [51][52][53][54][55][56] As a consequence, one-pot processes using heterogeneous organocatalyts, either in combination with soluble catalysts or using multifunctional catalytic materials became one of the preferred ways of increasing the sustainability of preparation of chiral fine chemicals. Due to the larger numbers of such materials, it was expedient to subdivide this section according to the type of immobilized organocatalyst.…”

“…[41][42][43][44][45] During the last decade, the availability of a large variety of chiral catalysts [7][8][9][10][11][12][13][14][15][16][17][18][19] has been the driving force for the development of asymmetric catalytic one-pot procedures. [46][47][48][49][50][51][52][53][54][55][56] Such reactions could be applied in the synthesis of optically pure building blocks and active pharmaceuticals. [36][37][38][39] Enzymes, chiral metal complexes and organocatalysts, either as single catalysts or their various combinations with achiral or a second chiral catalyst, have been used in these reactions, allowing the preparation of complex organic molecules such as natural products and other bioactive compounds by significantly simplified procedures.…”

“…processes catalysed by combinations of enzymes and inorganic heterogeneous catalysts, by bio-nanocatalysts, or aminocatalysts combined with metals. 56,63,64 The aim of the present review is to give a comprehensive survey of the asymmetric one-pot reactions in which heterogeneous chemical catalysts have been applied. Those procedures are included in which in a catalysed step stereoselective formation of at least one new chiral centre occurs.…”

Lichtgetriebene Ein‐Elektronen‐Transferprozesse als Funktionsprinzip in der Schwefel‐ und Selen‐Multikatalyse

“…Bei genauerer Betrachtung der einzelnen Ausprägungsformen von Multikatalyseprozessen zeigen sich weitere Vorzüge dieser Form der Reaktionsführung (Schema ) . So wird bei den am häufigsten anzutreffenden Klassifikationen von Multikatalysen zwischen A) der kooperativen Dualkatalyse und B) der multifunktionalen Katalyse– einerseits sowie C) der gekoppelt‐restaurativen Katalyse, D) der doppelt aktivierenden Katalyse und E) vielfältigen Formen der Tandemkatalyse (z. B. Relay‐, Kaskaden‐ und Dominokatalysen) andererseits unterschieden.…”

“…Kategorie C bezieht sich auf katalytische Redoxprozesse, in denen der Umsatz der Substrate in die entsprechenden Produkte mit einer Veränderung der Oxidationsstufe des Katalysators einhergeht . Um die Ausgangsoxidationsstufe dieses Katalysators wiederherzustellen, reagiert er mit einem weiteren Redoxkatalysator oder gar einer ganzen Kaskade von Redoxkatalysatoren, sodass insgesamt ein Transport von Elektronen zwischen den Edukten und den terminalen Redoxäquivalenten aufrechterhalten wird.…”