Recent Synthetic Applications Research Articles

Direct activation of relatively unstrained carbon-carbon bonds in homogeneous systems.

New modes of chemical reactivity are of high value to synthetic organic chemistry. In this vein, carbon-carbon (C-C) activation is an emerging field that offers new possibilities for synthesizing valuable complex molecules. This review discusses the pioneering stoichiometric discoveries in this field up to the most recent synthetic applications that apply catalytic transformations. Specifically, the review focuses on C-C activation in relatively unstrained systems, including stoichiometric reactions, chelation-directed and chelation-free catalytic reactions. While the field of C-C activation of relatively unstrained systems is underdeveloped, we expect that this review will provide insight into new developments and pave the path for robust, practical applications.

Recent Synthetic Developments and Applications of the Ullmann Reaction. A Review

Click to increase image sizeClick to decrease image size Acknowledgement We thank financial support from the National Institutes of Health grant (R15AI092315).

Computational fluid dynamics study of the synthesis process for a PET radiotracer compound, [11C]raclopride on a microfluidic chip

Recent synthetic applications conducted on microfluidic chips have shown improved yields and shorter reaction times as compared to conventional methods. These have generated great interest in the microfluidic synthesis of radiotracer compounds with short lived radioisotopes, such as carbon-11 (t1/2 – 20.4min). For the purpose of microreactor design optimization and to predict synthetic behavior, we launched a study of the radiosynthesis of [11C]raclopride on three different microchip designs by computational fluid dynamics, using COMSOL Multiphysics®. COMSOL's Reaction Engineering Lab® tool and convection and diffusion models were used first to investigate the “ideal” reactor and then to study reaction progress in the microchip geometry. Examining the concentration distribution within the microchannel geometry, it was clear that the microchannel length can predict passive mixing and higher product generation than microchannel length. Reducing the flow rate of reagents, premixing the reagents, and increasing reagent concentrations also increased product generation due to increased space times and molecular interactions. For the purpose of simulation, the yield is undesirably reduced by decreasing the diffusion coefficient and the reaction rate constant. This study provides the optimized parameters to redesign the microchip in order to increase the efficiency of micromixing within the microchannels and, therefore, increase the reaction yield.

Reinvestigation of Mucohalic Acids: Recent Development and Application in Drug Discovery

The recent synthetic development and applications of mucochloric acid,mucobromic acid and their derivatives are described,mainly focus on our work using these multiple functional molecules to access a wide variety of γ-butenolides,γ-lactams,4,5-dihalopyridazin-3-ones and other novel,multi-functionalized building blocks and pharmaceutical products.

ChemInform Abstract: Recent Applications of gem‐Dichloroepoxide Intermediates in Synthesis

AbstractReview: 67 refs.

Recent applications of gem-dichloroepoxide intermediates in synthesis

This review highlights recent synthetic applications of the Jocic-Reeve, Corey-Link, and Bargellini reactions, all of which proceed through reactive gem-dichloroepoxide intermediates. Research published between 2001-early 2011 involving enhancements to the named reactions, new synthetic methods, target-directed synthesis, and drug discovery and development is emphasized.

Shining Light on Photoredox Catalysis: Theory and Synthetic Applications

Photoredox catalysis is emerging as a powerful tool in synthetic organic chemistry. The aim of this synopsis is to provide an overview of the photoelectronic properties of photoredox catalysts as they are applied to organic transformations. In addition, recent synthetic applications of photoredox catalysis are presented.

Arylsulfonyl Group: Activating Properties and Recent Synthetic Applications

The carbanion stabilizing effect induced by the arylsulfonyl group has dominated and typified the chemistry of this functional entity for a long time. In addition to this important feature, the activity of the arylsulfonyl moiety as a leaving group has been exploited and a plethora of exciting synthetic applications have been found. The base- or acid-promoted elimination of the sulfonyl group from of α-amido sulfones and sulfonyl indoles is able to produce the in situ generation of reactive N-acylimino and alkylideneindolenine intermediates that can be used in the diastereo and enantioselective synthesis of various amino and heterocyclic compounds.

β -Nitroacrylates as an Emerging, Versatile Class of Functionalized Nitroalkenes for the Synthesis of a Variety of Chemicals

Modern organic synthesis requires easily obtainable synthetic building blocks that can be manipulated without the need of severe reaction conditions and that show high chemical versatility so that they can be employed in diverse synthetic processes. β- Nitroacrylates are a class of electron-poor alkenes having two electron-withdrawing groups in α- and β-positions. This peculiarity makes their chemical behaviour more interesting with respect to the classical conjugated nitroalkenes and, in the last few years, there has been a growing interest in the chemistry of these molecules. The aim of this report is to present, mainly, the recent synthetic applications of β- nitroacrylates, as well as the principal procedures for their preparations.

Editorial: Crystal‐Clear View of Chemistry

Editorial: Crystal‐Clear View of Chemistry

The Missing Link Between Molecular Triplets and Spin-Polarized Free Radicals: Room Temperature Triplet States of Nanocrystalline Radical Pairs

Photochemical reactions of organic molecules in the solid state have an excellent potential in green chemistry technologies as they often proceed in high yields to give a single product without generating volatile organic solvent waste. While recent synthetic applications highlight the need for a better understanding of reaction mechanisms and kinetics, spectroscopic observations of excited states and short-lived intermediates in single crystals and powdered samples have been extremely challenging due to the high optical density and scattering power of single crystals and powdered samples. In this communication, we report the first direct observation of a radical pair triplet state by time-resolved electron paramagnetic resonance (TREPR) with nanocrystals of 4,4'-dimethoxy-dicumyl ketone (1OMe) suspended in water. Steady state irradiation of 1OMe had previously shown that reactions in dry powders and nanocrystalline suspensions proceed with high efficiency and chemoselectivity to generate 4,4'-dimethoxy-dicumene 2OMe by decarbonylation and radical coupling. The nanocrystalline suspensions were excited with an 25 ns laser pulse at 308 nm using a flow system within the cavity of a time-resolved EPR spectrometer. The resulting TREPR spectra showed strong spin polarization with enhanced absorption A and emission E signals in an AAAEEE pattern characteristic of a randomly oriented triplet with zero-field splitting parameters D = 243 G and E = 11 G as well as an isotropic exchange integral J = -45,000 G. The assignment of this spectrum to a radical pair triplet state was supported by measurements carried out in fluid solution and in frozen glasses, which allowed for the characterization of the free radical and the triplet excited molecular state of the starting ketone 1OMe.

ChemInform Abstract: Recent Synthetic Applications of Manganese in Organic Synthesis

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Recent advances in enantioselective copper-catalyzed 1,4-addition

A comprehensive overview of recent literature from 2003 concerning advances in enantioselective copper catalysed 1,4-addition of organometallic reagents to alpha,beta-unsaturated compounds is given in this critical review. About 200 ligands and catalysts are presented, with a focus on stereoselectivities, catalyst loading, ligand structure and substrate scope. A major part is devoted to trapping and tandem reactions and a variety of recent synthetic applications are used to illustrate the practicality and current state of the art of 1,4-addition of organometallic reagents. Finally several mechanistic studies are discussed (162 references).

Domino reactions of rhodium(ii) carbenoids for alkaloid synthesis

In this tutorial review, the rhodium(II)-catalyzed domino reactions of alpha-diazo carbonyl compounds are summarized. The article will emphasize some of the more recent synthetic applications of the rhodium carbenoid cyclization/cycloaddition domino cascade for alkaloid synthesis. The many structurally diverse and highly successful examples of both oxa and azapolycyclic ring formation cited in this tutorial review clearly demonstrate that the domino cyclization/cycloaddition cascade of metallo carbenoids has evolved as an important strategy for the synthesis of nitrogen containing natural products.

Recent Synthetic Applications of Manganese in Organic Synthesis

While the organometallic compounds derived from many metals have found a broad application in organic synthesis, the use of organomanganese compounds has only recently been developed due to the passivity exhibited by commercial Mn in the direct metalation of organic compounds. In this Concept article, we highlight the potential of manganese and its organometallic compounds in organic synthesis by illustration of the studies previously reported by others and our laboratory in this field. Based on the transformations reported herein, organomanganese compounds could become important tools in the future of the organic synthesis, due to their high selectivity.

Oxidative Cyclization of Dienes and Polyenes Mediated by Transition-Metal-Oxo Species

During the last forty years, several groups have reported results concerning the oxidative cyclization of polyenes, mostly dienes, with transition-metal-oxo species such as permanganate, ruthenium tetroxide, perruthenate and osmium tetroxide, but only recently has a systematic study of some of these processes been undertaken. The formation in a single step of tetrahydrofuran, poly-tetrahydrofuran, tetrahydropyran and oxepane products with complete relative stereocontrol, and the unique postulated mechanisms, render these processes very appealing from both the synthetic and theoretical points of view. Recent synthetic applications of these oxidative transformations have highlighted their usefulness. This review summarizes the state of the art in this field, in an attempt to provide a comprehensive view of these processes. Some similarities between the chemistry of ruthenium tetroxide and rhenium(VII)-oxo species are highlighted.

Recent synthetic applications of the dealkoxycarbonylation reaction. Part 2. Dealkoxycarbonylations of β-keto esters, α-cyanoesters and related analogues

In Part 2, the synthetic applications of dealkoxycarbonylations of β-keto esters, α- cyano esters and related activated esters will be reviewed for the period 1981 to the middle of 2006. In Part 1, the dealkoxycarbonylations of malonate esters were reviewed for this same period.

Recent synthetic applications of the dealkoxycarbonylation reaction. Part 1. Dealkoxycarbonylations of malonate esters

The purpose of this review is to update (publications from 1981 to mid 2006) the synthetic applications of dealkoxycarbonylations of malonate esters, β-keto esters (and related esters with α-substituted electron-withdrawing functionalities) induced by heating with water or with water in the presence of salts (such as NaCN, NaCl or LiCl) in dipolar aprotic solvents. The presentation will be divided in two parts. In Part 1, discussion will focus on the dealkoxycarbonylations of malonate esters. Part 2 (to follow as a separate paper) will deal with the dealkoxycarbonylations of β-keto esters and α-cyano esters (and related analogues).

Palladium-mediated cascade or multicomponent reactions: A new route to carbo- and heterocyclic compounds

Abstract In recent years, new processes based on transition-metal-mediated intramolecular addition reaction of heteronucleophiles and stabilized carbon nucleophiles to unactivated alkenes and alkynes have been developed in our laboratory. In this article, we summarize a number of recent synthetic applications of these new processes. Emphasis is placed on the development of multicomponent reactions based on a Pd-mediated intramolecular cyclization coupled with a carbon-carbon bond-forming reaction. Applications of this methodology to the synthesis of natural lignans are also reported.

Catalytic Decomposition of Diazo Compounds as a Method for Generating Carbonyl‐Ylide Dipoles

AbstractFor Abstract see ChemInform Abstract in Full Text.