Application of silver-promoted reactions in the synthesis of five-membered O-heterocycles

The investigation of facial protocols for chemical synthesis is a growing area of interest due to increasing environmental issues. The use of catalysts in organic reactions has gained extensive interest. Metal and nonmetal catalysts provided a new improved alternative to traditional methods in modern synthetic chemistry. The aim of the present review is to focus on the applications of silver-promoted reactions for the synthesis of oxygen containing five-membered heterocycles which have significance in organic synthesis, pharmaceuticals, agrochemicals, and among others.     

Metal and organo-complex promoted synthesis of fused five-membered O-heterocycles

Abstract

One of the highly emerging and an important aspect of organic chemistry is the metal and organo-complex promoted synthesis of the heterocycles. The methodologies used earlier for its synthesis were less approachable to the organic chemist due to their high cost, highly sophisticated instrumentation and problematic methods. For both stereoselective and regioselective synthesis of fused five-membered O-containing heterocycles, cyclic reactions that are metal and organo-complex promoted have been known to be very efficient. The present review article covers the different applications of metals and organo-complexes in the formation of fused five-membered oxygen containing fused heterocycles. The fascinating research that has been done in this area is enclosed in this review.     

Ag-mediated synthesis of six-membered N-heterocycles

Abstract

One of the highly emerging and an important aspect of organic chemistry is the metal catalyzed synthesis of heterocycles. The methods used earlier for the synthesis of heterocycles were significant in the organic synthesis and developing cost-effective, improved and facial methods were beneficial to construct the complex architectures. For the both stereoselective and regioselective synthesis of six-membered nitrogen containing heterocycles, cyclic reactions that are Ag-mediated have known to be very efficient. The present review covers the applications of Ag in the formation of six-membered nitrogen containing heterocycles.     

Cu-assisted C–N bond formations in six-membered N-heterocycle synthesis

Abstract

One of the highly emerging and important aspect of organic chemistry is the metal-catalyzed synthesis of the heterocycles. The methodologies used earlier for its synthesis were less approachable to the organic chemist because of their high cost, highly specified instrumentation and inconvenient methods. For both the stereoselective and regioselective synthesis of six-membered nitrogen-containing heterocycles, cyclic reactions that are Cu-catalyzed have known to be very efficient. The presented review covers the varied applications of Cu as a catalyst and its importance in the formation of six-membered nitrogen-containing heterocycles. The fascinating research that has been done in this area is also enclosed in this review.     

Seven-membered N-heterocycles: metal and nonmetal assisted synthesis

The investigation of facial synthetic methods for chemical synthesis is a growing area of interest due to increasing environmental issues. The use of catalysts in organic reactions has gained extensive interest. Metal and nonmetal catalysts provided a new improved alternative to traditional methods in modern synthetic chemistry. The aim of the present review is to focus on the applications of metals and nonmetals for the synthesis of seven-membered N-heterocycles.     

Photochemical mediated reactions in five-membered O-heterocycles synthesis

Photochemical mediated synthesis in organic chemistry is a highly expanding area. This is a widely exploited area of research for the construction of new pharmaceutically significant heterocycles. Recently many reports appeared for the synthesis of heterocycles photochemically due to a wide range of biological activities associated with them. In this article, I have described the synthesis of a number of oxygen-bearing five-membered heterocycles.     

Seven and higher-membered oxygen heterocycles: Metal and non-metal

The investigation of methods for the chemical synthesis is a growing area of interest due to increasing environmental issues. The use of catalysts in organic reactions has gained extensive interest. Metal and nonmetal catalysts provided a new improved alternative to traditional methods in modern synthetic chemistry. The aim of present review is to focus on the applications of metals and nonmetals for the synthesis of seven and higher-membered O-heterocycles.     

The CO/PC analogy in coordination chemistry and catalysis

This short account summarizes recent results obtained in the coordination chemistry of phosphinines and emphasizes their analogy with CO ligands. Reduced complexes can be easily assembled through the reaction of reduced 2,2′-biphosphinine dianions with transition metal fragments. Theoretical calculations were performed to establish the oxidation state of the metal in these complexes. Though many reduced complexes are available, phosphinines proved to be too sensitive toward nucleophiles to be used as efficient ligands in most catalytic processes. However, the high electrophilicity of the phosphorus atom can be exploited to synthesize phosphacylohexadienyl anions which exhibit a surprising coordination chemistry. When phosphino sulfide groups are incorporated as ancillary tridentate anionic SPS ligands can be easily produced. These ligands can bind different transition metal fragments such as M-X (M = group 10 metal, X = halogen), Rh-L (L = 2 electron donor ligand), Cu-X and Au-X (X = halogen). Palladium(II) complexes proved to be active catalyst in the Miyaura cross-coupling reaction. Bidentate anionic PS ligands were also synthesized following a similar approach. Their Pd(II) (allyl) derivatives showed a very good activity in the Suzuki catalyzed cross-coupling process that allows the synthesis of biphenyl derivatives through the reaction of phenylboronic acid with bromoarenes.     

Nickel catalysis: six membered heterocycle syntheses

Abstract

The investigation of methods for the chemical synthesis is a growing area of interest due to increasing environmental issues. The use of catalysts in organic reactions has gained extensive interest. Metal and nonmetal catalysts provide a new improved alternative to traditional methods in modern synthetic chemistry. The aim of present review is to focus on the applications of nickel for the synthesis of six membered heterocylces.     

Green synthesis of three- to five-membered O-heterocycles using ionic liquids

The investigation for replacement of organic solvents in organic synthesis is a growing area of interest due to increasing environmental issues. The use of ionic liquid salts as solvents and catalysts in organic reactions has gained extensive interest. Ionic liquids provided a new environmentally benign and improved alternative to traditional methods in modern synthetic chemistry. The aim of present review is to focus on the applications of ionic liquids for the synthesis of O-heterocycles.     

Multiple nitrogen-containing heterocycles: Metal and non-metal assisted synthesis

A wide variety of biological activities are possessed by N-, O-, and S-containing heterocycles and recently many reports appeared for the synthesis of these heterocycles. The synthesis of heterocycles with the help of metal and nonmetal became highly rewarding and important method in organic synthesis. This review article concentrated on the synthesis of multiple-nitrogen containing five-membered heterocylces in the presence of metal and nonmetal. It describes the formation of five-, six-, and seven-membered heterocyclic rings.     

Vinyl Dihydropyrans and Dihydrooxazines: Cyclizations of Catalytic Ruthenium Carbenes Derived from Alkynals and Alkynones

A novel synthesis of 2‐vinyldihydropyrans and dihydro‐1,4‐oxazines (morpholine derivatives) from alkynals and alkynones has been developed. The cyclizations require a mild generation of catalytic ruthenium carbenes from terminal alkynes and (trimethylsilyl)diazomethane followed by trapping with carbonyl nucleophiles. Mechanistic aspects of the new cyclizations are discussed.     

Ring Expansion and Skeletal Rearrangement of Propargyl Alcohol Substituted Aziridines Induced by Ruthenium Complexes

The ring expansion and skeletal rearrangement of two types of propargyl alcohol substituted aziridines with or without cycloalkane moieties was induced by a ruthenium cyclopentadienyl phosphine complex. In the simple aziridine system with no cycloalkane, the unique cycloisomerization process altered the absolute connectivity of the two‐carbon unit in the three‐membered ring to give organometallic products with substituted pyridine or dihydropyridine ligands. For the aziridine on a cyclohexyl ring, the cycloisomerization process was controlled by an interchange process between vinylidene and allenylidene species, thus creating a better relative configuration of the aziridinyl and the alkynyl units. This determines the stereochemistry of the metal carbene products of the octahydroindole derivatives. The structures of five products were determined by X‐ray diffraction analysis.     

Applications of palladium dibenzylideneacetone as catalyst in the synthesis of five-membered N-heterocycles

A wide variety of biological activities are possessed by N, O, and S containing heterocycles and recently many reports appeared for the synthesis of these heterocycles. The synthesis of heterocycles with the help of metal became highly rewarding and important method in organic synthesis. This review article concentrated on the synthesis of nitrogen containing five-membered heterocylces in the presence of palladium dibenzylideneacetone as a catalyst.     

Palladium acetate assisted synthesis of five-membered N-polyheterocycles

Abstract

The metal-assisted synthesis of heterocyclic compounds is known to be one of the extremely developing as well as significant concepts of organic chemistry. Because of their expensive, complex working of the instrument and difficult procedures, the methodologies used earlier for the heterocycle synthesis were less amicable to the researchers. The Pd(OAc)₂-mediated cyclic reactions have been recognized to be very effective for both the stereoselective as well as regioselective formation of the 5-membered N-bearing heterocyclic compounds. The different uses of palladium acetate, as a catalyst in the formation of 5-membered N-containing polyheterocycles, are covered in this review article.     

Recent developments in the synthesis of nitrogen containing five-membered polyheterocycles using rhodium catalysts

The nitrogen-, oxygen- and sulfur-heterocycles possess a number of pharmacological activities and recently many reports appeared for the synthesis of these heterocycles. In few past years, metals are applied for the production of these heterocycles. These synthetic strategies involving metal catalysts became highly significant in the synthetic organic chemistry. This review article features the applications of rhodium metal catalysts for the preparation of five-membered N-polyheterocylces.     

Structure–Reactivity Relationships in the Hydrogenation of Carbon Dioxide with Ruthenium Complexes Bearing Pyridinylazolato Ligands

Pyridinylazolato (N–N′) ruthenium(II) complexes of the type [(N–N′)RuCl(PMe₃)₃] have been obtained in high yields by treating the corresponding functionalised azolylpyridines with [RuCl₂(PMe₃)₄] in the presence of a base. ¹⁵N NMR spectroscopy was used to elucidate the electronic influence of the substituents attached to the azolyl ring. The findings are in agreement with slight differences in the bond lengths of the ruthenium complexes. Furthermore, the electronic nature of the azolate moiety modulates the catalytic activity of the ruthenium complexes in the hydrogenation of carbon dioxide under supercritical conditions and in the transfer hydrogenation of acetophenone. DFT calculations were performed to shed light on the mechanism of the hydrogenation of carbon dioxide and to clarify the impact of the electronic nature of the pyridinylazolate ligands.