Recent developments in multicomponent synthesis of structurally diversified tetrahydropyridines
TL;DR: In this article, a review of the advancement made in the field of multicomponent synthesis of tetrahydropyridines and their derivatives of the last few years is presented.
Abstract: Tetrahydropyridines (THPDs) have been recognized as a major constituent of naturally occurring alkaloids. Being heterocyclic nitrogenous compounds, they therefore display robust biological and pharmacological profiles. In this context, they are fascinating synthetic targets in synthetic chemistry and as a consequence of this their synthesis through simple and convenient tactics has emerged as an important and challenging task. To meet such challenge, multicomponent reactions (MCRs) are employed as an excellent tool for achieving compounds containing complex diversity in single step and production of their vast libraries. This review represents the advancement made in the field of multicomponent synthesis of THPDs and their derivatives of the last few years.
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TL;DR: A collection of examples on recent developments in organic bond formation reactions like carbon–carbon, carbon–nitrogen (C–N), carbon–oxygen (C-O), carbon-halogen (C –X), etc. is documented.
Abstract: With the growing interest in renewable energy and global warming, it is important to minimize the usage of hazardous chemicals in both academic and industrial research, elimination of waste, and possibly recycle them to obtain better results in greener fashion. The studies under the area of mechanochemistry which cover the grinding chemistry to ball milling, sonication, etc. are certainly of interest to the researchers working on the development of green methodologies. In this review, a collection of examples on recent developments in organic bond formation reactions like carbon–carbon (C–C), carbon–nitrogen (C–N), carbon–oxygen (C–O), carbon–halogen (C–X), etc. is documented. Mechanochemical syntheses of heterocyclic rings, multicomponent reactions and organometallic molecules including their catalytic applications are also highlighted.
163 citations
TL;DR: The multicomponent Mannich reaction is a green and classical method for the preparation of β-aminoketones and β-aminoaldehydes (Mannich bases) and, as such, is one of the most important reactions in organic chemistry as discussed by the authors.
86 citations
TL;DR: The current manuscript describes the use of a heteropolyacid-containing task-specific ionic liquid, supported in imidazolium-based ionic liquids, as the catalyst for an efficient multicomponent synthesis of hexahydroimidazo[1,2-α]pyridine derivatives.
Abstract: The current manuscript describes the use of a heteropolyacid-containing task-specific ionic liquid, supported in imidazolium-based ionic liquids, as the catalyst for an efficient multicomponent synthesis of hexahydroimidazo[1,2-α]pyridine derivatives. The reactions conditions were fully optimized, and the bridgehead nitrogen heterocycle derivatives could be obtained in just 1 h exclusively as a single isomer ( trans). Single crystal X-ray analysis confirmed the trans derivative as the only isomer. The mechanism of the reaction was investigated by ESI(+)-MS(/MS), and the use of the elegant charge-tag strategy allowed a catalytic cycle to be proposed for the current transformation and revealed the possibility of at least two reaction pathways. One derivative bearing a coumarin scaffold was synthesized, and its fluorescent properties allowed it to be tested as a probe for live-cell imaging experiments with a preference for mitochondria.
56 citations
TL;DR: The problems of a lack of mechanistic knowledge and the importance of the rational design of new catalytic systems, considering the possible noncovalent interactions aimed towards designing "flexible" and adaptative catalysts to fit the key intermediates and reagents, are discussed in light of new concepts and trends.
Abstract: This critical review focuses on some key features which determine successful enantioselective catalysed multicomponent reactions (MCRs) and are typically underappreciated in the literature. A critical analysis of this topic is of current interest and the importance of elucidating the reaction mechanism of a MCR, which is usually a neglected task, is a feature of analysis that is aimed at successfully achieving the enantioselective version of the reaction by proper comprehension of the transformation. The key role of noncovalent interactions is another feature analysed along with the transition state (TS) of the key step for the chiral induction of some selected MCRs. In this critical review, the problems of a lack of mechanistic knowledge and the importance of the rational design of new catalytic systems, considering the possible noncovalent interactions aimed towards designing "flexible" and adaptative catalysts to fit the key intermediates and reagents, are discussed in light of new concepts and trends.
42 citations
TL;DR: In this article, simple and efficient protocols have been developed for the synthesis of diversely functionalized dihydro-2-oxypyrroles and tetrahydropyridines.
Abstract: Simple and efficient protocols have been developed for the synthesis of diversely functionalized dihydro-2-oxypyrroles and tetrahydropyridines. One-pot four-component reaction of dialkyl acetylenedicarboxylates, amines and formaldehyde in the presence of 2,6-pyridinedicarboxylic acid in methanol at room temperature provides dihydro-2-oxypyrroles. The combination of β-ketoesters, aromatic aldehydes and amines yielded tetrahydropyridine derivatives under the same reaction conditions. The salient features of these methods are mild reaction conditions, reduced reaction time, moderate to high yields, applicability to a broad range of substrates and no tedious column chromatographic separation.
33 citations
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3,685 citations
TL;DR: MCRs and especially MCRs with isocyanides offer many opportunities to attain new reactions and basic structures, however, this requires that the chemist learns the "language" of M CRs, something that this review wishes to stimulate.
Abstract: Multicomponent reactions (MCRs) are fundamentally different from two-component reactions in several aspects. Among the MCRs, those with isocyanides have developed into popular organic-chemical reactions in the pharmaceutical industry for the preparation of compound libraries of low-molecular druglike compounds. With a small set of starting materials, very large libraries can be built up within a short time, which can then be used for research on medicinal substances. Due to the intensive research of the last few years, many new backbone types have become accessible. MCRs are also increasingly being employed in the total synthesis of natural products. MCRs and especially MCRs with isocyanides offer many opportunities to attain new reactions and basic structures. However, this requires that the chemist learns the “language” of MCRs, something that this review wishes to stimulate.
3,619 citations
TL;DR: The underlying reaction based principles of transition-metal catalysis in multi-component syntheses of heterocycles, summarizes recent developments of palladium catalyzed MCR, and highlights the more recent contributions to MCR based heterocyclic synthesis by virtue of rhodium, ruthenium, and copper catalysis are outlined.
Abstract: For a long time multi-component syntheses of heterocycles have undeniably been a domain of classical carbonyl condensation chemistry. However, the advent of transition-metal catalysis not only has fertilized strategies in heterocyclic synthesis by uni- and bimolecular transformations but the past decade has also witnessed a rapid development of transition-metal catalysis in new multi-component reactions (MCR). Expectedly, palladium catalyzed processes have received a dominant position, yet, other transition-metal complexes are catching up implying organometallic elementary steps that reach even further than cross-coupling and carbometallation. Besides domino MCRs that are purely based upon organometallic catalysis the sequential and consecutive combination with condensation, addition and cycloaddition steps opens a vast playground for the invention of new sequences in heterocyclic synthesis. This tutorial review outlines the underlying reaction based principles of transition-metal catalysis in multi-component syntheses of heterocycles, summarizes recent developments of palladium catalyzed MCR, and highlights the more recent contributions to MCR based heterocyclic synthesis by virtue of rhodium, ruthenium, and copper catalysis.
889 citations
TL;DR: In this paper, the Einwirkung von Schwefel auf vinyloge methylenaktive Nitrile, gestattet auch die Einbeziehung von Alkylarylketonen in die Reaktion.
Abstract: Aliphatische Ketone, Aldehyde sowie β-Dicarbonylverbindungen reagieren mit methylenaktiven Nitrilen und Schwefel in Gegenwart von Aminen bei Raumtemperatur zu 2-Aminothiophenen. — Eine Variante der Synthese, die Einwirkung von Schwefel auf vinyloge methylenaktive Nitrile, gestattet auch die Einbeziehung von Alkylarylketonen in die Reaktion.
700 citations
404 citations