Multicomponent reaction comprising one-pot installation of bidentate directing group and Pd(II)-catalyzed direct β-arylation of C(sp3) H bond of aliphatic and alicyclic carboxamides

Diastereoselective palladium-catalyzed functionalization of prochiral C(sp3)-H bonds of aliphatic and alicyclic compounds

We highlight the reported developments of the palladium-catalyzed C-H activation and functionalization of the inactive/unreactive prochiral C(sp³)-H bonds of aliphatic and alicyclic compounds. There exist numerous classical methods for generating contiguous stereogenic centers in a compound with a high degree of stereocontrol. Along similar lines, the Pd(II)-catalyzed, directing group-aided functionalization of inactive prochiral/diastereotopic C(sp³)-H bonds have been exploited to accomplish the stereoselective construction of stereo-arrays in organic compounds. We present a concise discussion on how specific strategies consisting of Pd(II)-catalyzed, directing group-aided C(sp³)-H functionalization have been utilized to generate two or more stereogenic centers in aliphatic and alicyclic compounds.

Ag-Catalyzed Multicomponent Synthesis of Heterocyclic Compounds: A Review

The investigation of the procedures for the multi-component synthesis of heterocycles has attracted the interest of organic and medicinal chemists. The use of heterogeneous catalysts, especially transition metal catalysts in organic synthesis, can provide a new, improved alternative to traditional methods in modern synthetic chemistry. The main focus is on the utilization of silver as a catalyst for the multi-component synthesis of heterocyclic compounds. The present review describes some important reported studies for the period of 2010 to 2020. Conclusion: The present review addresses some of the important reported studies on multi-component synthesis of heterocycles in the period of 2010-2020. These approaches were performed under classical and nonclassical conditions, using Ag salts, Ag NPs, Ag on the support, Ag as co-catalysts with other transition metals, ionic liquids, acidic or basic materials. Most of the reported reactions were performed under solvent-free conditions or in green solvents and the utilized catalysts were mostly recyclable. The main aim of the present review is to provide the organic chemists with the most appropriate procedures in the multi-component synthesis of desired heterocycles using silver catalysts.

A Guide to Directing Group Removal: 8-Aminoquinoline

The use of directing groups allows high levels of selectivity to be achieved in transition metal-catalyzed transformations. Efficient removal of these auxiliaries after successful functionalization, however, can be very challenging. This review provides a critical overview of strategies used for removal of Daugulis' 8-aminoquinoline (2005-2020), one of the most widely used N,N-bidentate directing groups. The limitations of these strategies are discussed and alternative approaches are suggested for challenging substrates. Our aim is to provide a comprehensive end-users' guide for chemists in academia and industry who want to harness the synthetic power of directing groups-and be able to remove them from their final products.

Step-Economical C–H Activation Reactions Directed by In Situ Amidation

Owing to the inherent ability of amides to chelate transition-metal catalysts, amide-directed C–H activation reactions constitute a major tactic in directed C–H activation reactions. While the conventional procedures for these reactions usually involve prior preparation and purification of amide substrates before the C–H activation, the step economy is actually undermined by the operation of installing the directing group (DG) and related substrate purification. In this context, directed C–H activation via in situ amidation of the crude material provides a new protocol that can significantly enhance the step economy of amide-directed C–H activation. In this short review, the advances in C–H bond activation reactions mediated or initiated by in situ amidation are summarized and analyzed.

1 Introduction

2 In Situ Amidation in Aryl C–H Bond Activation

3 In Situ Amidation in Alkyl C–H Bond Activation

4 Annulation Reactions via Amidation-Mediated C–H Activation

5 Remote C–H Activation Mediated by Amidation

6 Conclusion

Bidentate Directing Groups: An Efficient Tool in C-H Bond Functionalization Chemistry for the Expedient Construction of C-C Bonds

During the past decades, synthetic organic chemistry discovered that directing group assisted C-H activation is a key tool for the expedient and siteselective construction of C-C bonds. Among the various directing group strategies, bidentate directing groups are now recognized as one of the most efficient devices for the selective functionalization of certain positions due to fact that its metal center permits fine, tunable, and reversible coordination. The family of bidentate directing groups permit various types of assistance to be achieved, such as N,N-dentate, N,O-dentate, and N,S-dentate auxiliaries, which are categorized based on the coordination site. In this review, we broadly discuss various C-H bond functionalization reactions for the formation of C-C bonds with the aid of bidentate directing groups.

Palladium-catalyzed multicomponent reactions: an overview

This first review on this topic focuses on the developments in the chemistry of Pd-catalyzed multi-component reactions (MCRs). MCRs are generally atom economic, ideal and eco-friendly reactions, and often the final products are generated almost without any by-products. In this review, the developments in Pd-catalyzed MCRs are categorized based on the products formed such as acyclic compounds, carbocyclic compounds, heterocyclic compounds and miscellaneous compounds. MCRs have great applications in various fields like medicinal chemistry, combinatorial synthesis, heterocyclic chemistry etc. and this review covers the literature up to 2019.

A comprehensive overview of directing groups applied in metal-catalysed C-H functionalisation chemistry

The present review is devoted to summarizing the recent advances (2015-2017) in the field of metal-catalysed group-directed C-H functionalisation. In order to clearly showcase the molecular diversity that can now be accessed by means of directed C-H functionalisation, the whole is organized following the directing groups installed on a substrate. Its aim is to be a comprehensive reference work, where a specific directing group can be easily found, together with the transformations which have been carried out with it. Hence, the primary format of this review is schemes accompanied with a concise explanatory text, in which the directing groups are ordered in sections according to their chemical structure. The schemes feature typical substrates used, the products obtained as well as the required reaction conditions. Importantly, each example is commented on with respect to the most important positive features and drawbacks, on aspects such as selectivity, substrate scope, reaction conditions, directing group removal, and greenness. The targeted readership are both experts in the field of C-H functionalisation chemistry (to provide a comprehensive overview of the progress made in the last years) and, even more so, all organic chemists who want to introduce the C-H functionalisation way of thinking for a design of straightforward, efficient and step-economic synthetic routes towards molecules of interest to them. Accordingly, this review should be of particular interest also for scientists from industrial R&D sector. Hence, the overall goal of this review is to promote the application of C-H functionalisation reactions outside the research groups dedicated to method development and establishing it as a valuable reaction archetype in contemporary R&D, comparable to the role cross-coupling reactions play to date.

Transition metal-catalyzed C-H bond functionalization in multicomponent reactions: a tool toward molecular diversity

Transition metal-catalyzed C-H bond functionalization has numerous applications in organic synthesis as a powerful type of bond transformation. In particular, the combination of C-H functionalization with other types of chemical transformations in the manner of multicomponent reactions is an even more beneficial tool in the synthesis of small organic molecules because such reactions provide a platform for the rapid generation of high molecular diversity and complexity by making use of the advantages of both latent C-H bond transformation and the multicomponent reaction. Herein, we provide a review highlighting the research advances in the multicomponent reactions built upon transition metal-catalyzed C-H bond functionalization. The content spans from the reactions featuring the functionalization of C(sp³)-H, C(sp²)-H and C(sp)-H bonds over the last decade.