Cross-Dehydrogenative Coupling Reactions Between C(sp)-H and X-H (X = N, P, S, Si, Sn) Bonds: An Environmentally Benign Access to Heteroatom-Substituted Alkynes.

Form a green and sustainable chemistry point of view, cross-dehydrogenative coupling (or oxidative cross-coupling) reactions have been recognized as environmentally sustainable and atom economical synthetic routes for the construction of new carbon-carbon and carbon-heteroatom bonds, since no pre-functionalization of starting materials is required. In the past few years, the direct coupling of sp-hybridized C-H bonds with heteroatom-H bonds has received much attention because of the importance of heteroatom-substituted alkynes in organic and medicinal chemistry. This review examines the recent developments in cross-dehydrogenative coupling reactions between C(sp)-H and X-H (X = N, P, S, Si, Sn) bonds, with a particular focus on the mechanistic aspects of the reactions.

Recent developments in decarboxylative cross-coupling reactions between carboxylic acids and N-H compounds.

Carboxylic acids and their derivatives are ubiquitous compounds in organic chemistry, and are widely commercially available in a large structural variety. Recently, carboxylic acids have been frequently used as non-toxic and environmentally benign alternatives to traditional organohalide coupling partners in various carbon-carbon and carbon-heteroatom cross-coupling reactions. Along this line, several methods have been reported for the synthesis of nitrogen-containing organic compounds through decarboxylative cross-coupling reactions between carboxylic acids and N-H compounds. This review focuses on recent advances and discoveries on these reactions with special attention on the mechanistic aspects of the reactions.

Cycloaddition of atmospheric CO2 to epoxides under solvent-free conditions: a straightforward route to carbonates by green chemistry metrics.

The conversion of carbon dioxide (CO2) into value-added organic compounds has received more and more attention over recent years, not only because this gas is one of the major anthropogenic greenhouse gases, but also because it has been regarded as an abundant, inexpensive, nontoxic, nonflammable, and renewable one-carbon (C1) resource. Along these lines, the synthesis of five-membered cyclic carbonates employing CO2 as a safe alternative to toxic reagents such as phosgene or its derivatives is of great interest because of their wide range of applications in organic synthesis. However, most of CO2 incorporation reactions into carbonates are carried out in toxic and non-recyclable organic solvents. Furthermore, these transformations usually proceed at elevated pressures or supercritical CO2 conditions. Recently, several catalytic systems have been developed that allow the synthesis of functionalized carbonates from the reaction of atmospheric CO2 with corresponding epoxides under solvent-free conditions. This review is an attempt to summarize the most important advances and discoveries in this interesting research arena. The review is divided into three major sections. The first section will discuss ionic liquid catalyzed coupling reactions. The second will cover organocatalyzed reactions. The third focuses exclusively on metal-catalyzed fixations. Notably, the third section has been classified based on the metal element that carries out the catalysis (i.e. copper, palladium, zinc).

Recent advances in the application of nano-catalysts for Hiyama cross-coupling reactions.

This mini-review highlights the recent developments in the field of metal nanoparticle (NP) catalyzed Hiyama cross-coupling reactions. Most of the nanocatalysts outlined here allow convenient and green synthetic pathways for the construction of carbon-carbon bonds in water and fluoride-free conditions. Literature has been surveyed from 2005 to February 2018.

Solvent-free incorporation of CO2 into 2-oxazolidinones: a review.

This review is an attempt to give an overview on the recent advances and developments in the synthesis of 2-oxazolidinone frameworks through carbon dioxide (CO2) fixation reactions under solvent-free conditions. The cycloaddition of CO2 to aziridine derivatives is discussed first. This is followed by carboxylative cyclization of N-propargylamines with CO2 and three-component coupling of epoxides, amines, and CO2. Finally, cycloaddition of CO2 to propargylic alcohols and amines will be covered at the end of the review. The literature has been surveyed up until the end of 2018.

Cross-dehydrogenative coupling reactions between arenes (C-H) and carboxylic acids (O-H): a straightforward and environmentally benign access to O-aryl esters.

Transition-metal catalyzed cross-dehydrogenative-coupling reactions encompass highly versatile and atom economical methods for the construction of various carbon-carbon and carbon-heteroatom bonds by combining two C(X)-H (X = heteroatom) bonds. Along this line, direct acyloxylation of C-H bonds with carboxylic acids has emerged as a powerful and green approach for the synthesis of structurally diverse esters. In this focus-review we will describe recent progress in direct esterification of aromatic C-H bonds with special emphasis on the mechanistic features of the reactions. Literature has been surveyed until the end of February 2019.

DFT results against experimental data for electronic properties of C60 and C70 fullerene derivatives.

Some electronic properties of different C60 and C70 derivatives were evaluated using 20 density functionals (the B3LYP, BHANDH, PBE0, HSE06, CAM-B3LYP, ωB97X-D, BMK, PBEPBE, M06-L, M06, M06-2X, M06-HF, PW91PW91, BLYP, B97D, HCT407, τ-HCTH, τ-HCTHhyb, TPSS, and LSDA), and some of the results were compared with the available experimental data. Unlike in Hartree-Fock (HF) method, the orbital relaxation is not the origin of the violation of DFT from the Koopmans' theorem. For most of functionals, the HOMO-LUMO gap (Eg) is more sensitive to the functional compared to the optical gap. The functionals with a large %HF exchange significantly overestimate the Eg, and are not suggested for electronic calculations. All non-hybrid functionals underestimate the value of |HOMO| in comparison to the experimental ionization potential (IPe). In the hybrid functionals, the HOMO level becomes more stable by increasing %HF exchange and even in some functionals with a large %HF, |HOMO| overestimates the IPe.

Recent advances in sulfur-nitrogen bond formation via cross-dehydrogenative coupling reactions.

This focus-review surveys literature methods for the construction of sulfur-nitrogen bonds through cross-dehydrogenative coupling reactions between thiols and N-H compounds with a particular emphasis on the mechanistic aspects of the reactions. The literature has been surveyed until the end of 2017.

Advancements in six-membered cyclic carbonate (1,3-dioxan-2-one) synthesis utilizing carbon dioxide as a C1 source.

This review article surveys literature methods for the synthesis of six-membered cyclic carbonates using various substrates in the presence of CO2 with special emphasis on the mechanistic aspects of the reactions. We have classified these reactions based on the type of starting material.

Arylhydrazines: novel and versatile electrophilic partners in cross-coupling reactions.

Arylhydrazines are extremely valuable compounds in organic chemistry that are widely used for the synthesis of a variety of biologically active molecules such as indoles, indazoles, pyrazoles, aryltriazoles, ß-lactams and quinazolines. These compounds have also been widely utilized as arylation agents in oxidative cross-coupling reactions. In this review, we will highlight the most important explorations and developments in the carbon-carbon and carbon-heteroatom (nitrogen, phosphorus, sulfur, and selenium) cross-coupling of arylhydrazines. The literature has been surveyed from 2001 to June 2018.

A One-pot Condensation for Synthesis 2-methyl-4-phenylpyrano[3, 2-c] chromen-5(4H)-one and Synthesis of Warfarin by Ionic Liquid Catalysis.

The anticoagulant racemic warfarin is synthesized by the Michael addition of 4-hydroxycoumarin with benzalacetone in the present of equimolar amounts of imidazolium based ionic liquids [bmim] BF4 and [bmim] Br and other reaction solvents such as H2O, pyridine and ammonia in five different tests. Also synthesis of a derivative of warfarin (2-methyl-4-phenyl pyrano [3, 2-c] chromen-5(4H)-one) under solvent-free condition is reported. In this paper, we show the potential that ionic liquid have for the development of green methods for the formation of the C-C bond by reaction condensations without catalysts and organic solvents. A ،green method, according to the well-known principles, must reduce or eliminate the use or generation of unsafe substances. The work-up procedures were fairly simple and the products don>t require further purification.