Substituted phosphonates and phosphonic acids are well known for their diverse applications especially in medicinal chemistry and synthesis of agrochemicals. Among many structurally different phosphonates and phosphonic acids, the heterocyclic derivatives are scarcely described in literature, mostly because of the problems associated with their synthesis. Importantly those compounds are well known for their interesting physicochemical properties. In this personal account, achievements from our laboratory in the synthesis of substituted heterocyclic phosphonates and phosphonic acids are presented. The developed methods include not only the preparation of racemic mixtures but also effective protocols for asymmetric synthesis on new heterocyclic derivatives.
The pyrrolic framework is a ubiquitous motif encountered in both terrestrially- and marine-derived natural products. This review delineates various methods for the synthesis and manipulation of pyrrole and its derivatives as means for effecting the total synthesis of a diverse range of biologically active systems isolated from marine organisms. The examples presented here derive from the authors' longstanding activities in the area.
The structure, synthesis, reactivity and applications of the 1,2-oxathiine 2,2-dioxide ring system are reviewed. This relatively scarcely studied heterocycle can be accessed by a variety of traditional and modern synthetic chemistry strategies and offers great potential as a building block for the construction of acyclic and heterocyclic compounds. Furthermore, the delta-sultone ring is an invaluable reagent for imparting water solubility into a variety of materials including colorants and polymers.
The fundamentals and recent developments of sulfonium salts applied to the synthesis of oxygen heterocycles are reviewed. The chapter is divided into five sections, starting with the presentation of sulfonium salts and the methods to prepare them; then, application of Pummerer reactions (chemistry of the thionium ion generated from sulfoniums) is discussed. The cyclization of other sulfur species, such as sulfur ylides, is also described. Finally, the use of sulfoniums as sources of electrophiles to induce cyclization and to functionalize oxygen heterocycles is described.
This research account aims to highlight the use of organoselenium reagents and catalysts for the synthesis of heterocyclic scaffolds. Reaction promoted by selenium reagents are usually highly chemo-, regio- and stereoselective and the possibility to prepare diselenides having enantiomerically pure chiral centers offer a good approach for the enantioselective synthesis of heterocycles. Some examples of selenium containing heterocycles under investigations as promising anti SARS-CoV2 agents are also reported.
The transition-metal-catalyzed direct oxidative Heck-type reaction has made considerable progress in the last two decades. This review presents the recent advances in direct oxidative alkenylation of five- and six-membered heterocyclic ring systems containing nitrogen, oxygen or sulfur atom. This review focuses on the latest studies reported during the period from 2010 to early 2020 with emphasis on the reaction conditions.
Chromane derivatives are the core structure of many natural products, most of them having nutraceutical properties. As many natural products, this scaffold often carries out asymmetric carbon atoms. Therefore, asymmetric syntheses are of great importance in order to prepare these important building blocks. Our aim is to collect the asymmetric methods and some examples of total syntheses of natural product appeared in the literature in the last three years.
Synthesis and catalytic applications of supported imidazolium salts covalently linked to the proper support are described. As supports here we report, among others, the use of amorphous and mesoporous silica, polyhedral oligomeric silsesquioxanes, magnetic-based silica, polystyrenes, halloysite nanotubes, carbon nanoforms such as fullerenes, carbon nanotubes, carbon nanohorns, graphene. The catalytic applications have been divided into two main sections, metal-free based and metal-based reactions.
Organoselenium compounds play an increasingly important role in chemistry and biochemistry. Amongst the wide variety of selenium-containing systems, selena-heterocycles are versatile derivatives with broad applications in organic synthesis, catalysis, medicinal chemistry, and biology. In this context, taking into account the poor stability of most selenylating reagents or intermediates, the development of simple, mild and versatile synthetic methodologies towards functionalised selena-heterocycles remains an attractive yet challenging topic. This chapter will be focusing on recent advances on the synthesis of different classes of selenium-containing five- and six-membered ring systems.
Selenophenes are a special family of heterocyclic compounds present in several bioactive molecules and organic functional materials. In the past decade, several synthetic methodologies using harsh conditions were applied to their synthesis. In recent years, methods based on cheap reagents, mild and safer conditions, minimized steps, and high efficiency have been reported to produce diversely functionalized five-membered selenium rings. The present chapter is intended to review the most recent synthetic advances to furnish selenophene derivatives, their reactivity toward Pd-catalyzed C-H bond functionalization, and the preparation of selenoacenes.
This chapter provides an overview of transition-metals catalyzed reactions involving 2,3-substitutedquinolines as starting materials.
Organoboron complexes are one of the most investigated class of fluorescent dyes. Among them, 1,3,5,2-oxadiazaborinines, due to their unsymmetric structures, exhibit relatively large values of Stokes shift, which is attractive for optoelectronic applications of such compounds. The synthesis of oxadiazaborinines fluorescent dyes is based on the use of amide ligands, formed from different nitrogen-containing 2-aminoheterocycles (amidopyrazines, naphthyridine-2-amines, 2-aminopyridines, 2-aminopyridazines, 2-aminopyrimidines, 2-aminothiadiazoles, 2-aminothiazoles, and benzo[d]thiazol-2-amines). Among heteroaryl-fused oxadiazaborinines, (benzo)thiazolo[3,2-c][1,3,5,2] oxadiazaborinines demonstrate a remarkable chemical stability and can be efficiently postfunctionalized by organolithium-mediated electrophilation or Pd-catalysed cross-coupling reactions.
The development of novel methods for the selective functionalization and transformation of cyclobutanes is of great utility and has received significant attention in organic synthesis. Cyclobutanes play a significant role as building units because they can be easily transformed into a variety of interesting compounds by ring-expansion, -contraction and ring-opening reactions. In this account, we summarize our latest results on the use of 2-hydroxycyclobutanones as starting material of new tandem reactions leading to synthetically relevant nitrogen heterocycles.
Given the interest of coumarin-derived architectures as bioactive compounds and/ or naturally occurring products, the synthetic chemists have developed enantioselective syntheses of chiral derivatives with a focus on 3,4-disubstituted dihydrocoumarins. Nevertheless, essentially during the last decade, several reports highlighted the catalytic enantioselective syntheses of C3-substituted and C3-disubstituted analogues which encompass interesting synthetic and reactivity challenges. In this review, we have described the developments in that field of research with a focus on asymmetric sequences to have access to chiral dihydrocoumarins highlighting their useful synthetic transformations.
Imidazole derivatives are constituent of numerous natural compounds and many biologically active structures. In addition, imidazoles have been also successfully utilized as intermediaries in organic transformations for the synthesis of more elaborated structures. This characteristic makes them important substrates for further transformations. This chapter describes the efforts in the synthesis of imidazole derivatives using the reaction of alkynes with nitrogen-compounds under transition metal-catalyzed and metal-free conditions.
Various carbonylative reactions have been developed by our group to synthesize many heterocyclic compounds. In these methods, a number of convenient and efficient CO surrogates are employed such as metal carbonyls (Mo(CO)(6)), formic acid, formates (TFBen), and aldehydes (HMF).
1,10-Phenanthroline is a classical ligand in coordination chemistry which is renowned among bidentate ligands for the generality of its stable metal complexes widely studied across many fields of chemistry, physics, biology and medicine. In this review we provide a detailed summary of experimental procedures which were developed to perform transition-metal-catalyzed reactions with halo-1,10-phenanthrolines. These data are discussed using selected examples showing how these reactions allow to expand beyond the range of available phenanthroline derivatives.
1,2,4-Oxadiazoles are aromatic heterocycles with many valuable applications and interesting reactivity features. In this review, some recent advances in this field are presented with a particular emphasis on relevant applications as drugs. In fact, the 1,2,4-oxadiazole ring is widely present in a large range of drugs, here presented accordingly to their biological activity.
Palladium-catalyzed chemistry constitutes an important and growing area of research due to its exceptional synthetic versatility and selectivity. Indeed, no other transition metal acts as the catalyst of such a wide range of transformations. This account describes our efforts toward selectively promoting different palladium-catalyzed carbon-carbon bond-forming reactions for the synthesis of azaheterocycles. We have explored alternative ways of controlling the amphiphilic character of sigma-arylpalladium species in intramolecular coupling reactions with carbonyl compounds as well as the development of domino processes based on intramolecular palladium-catalyzed sigma-arylation reactions. Our results show that the outcome of the reaction with a given aryl halide can be finely tuned by adjusting the type of palladium catalyst and reaction conditions. As a consequence, diverse synthetic methodologies were developed to access high added value azahererocycles.
