Sole Reagent Research Articles

Simple and scalable electrochemical synthesis of 2,1-benzisoxazoles and quinoline N-oxides.

Cathodic reduction of the nitro moiety and subsequent intramolecular cyclization affords different substituted 2,1-benzisoxazoles and quinoline N-oxides. This methodology allows the synthesis of two different types of heterocycles from common simple starting materials, using electrons as a sole reagent for this transformation. The electrolysis can be conducted in a very simple undivided electrolysis cell under constant current conditions. This permits working on a larger scale compared to other electrochemical methodologies and represents a significant advantage.

A low-cost electrochemical thio- and selenocyanation strategy for electron-rich arenes under catalyst- and oxidant-free conditions.

A low-cost and efficient thio- and selenocyanation strategy for electron-rich arenes has been developed under constant-current electrolytic conditions in an undivided cell. This strategy is versatile for various (hetero)aromatic compounds such as indole, pyrrole, aniline and anisole under mild conditions without any catalyst or oxidant. Readily available salts NH4SCN and KSeCN are employed respectively as the sole reagent.

Oxidative Conversion of Sulfonyl Indoles into 3-Alkylidene-2-oxindoles under Flow Chemical Conditions

Sulfonyl indoles were converted into 3-alkylidene-2-oxindoles using NCS as the sole reagent under flow chemical conditions. The conjugated oxindole derivatives were generally obtained as E stereoisomers in moderate to satisfactory yields. The transformation entails the oxidation of the indole ring by NCS followed by elimination of arylsulfinic acid in order to install the exocyclic unsaturation.

An Organic Intermolecular Dehydrogenative Annulation Reaction.

The discovery of a direct method for the synthesis of three-ring heterocyclic carbazoles from unactivated arenes and anilides by a metal-free (organic) intermolecular dehydrogenative annulation reaction under ambient laboratory conditions is reported. Iodine(III) was used as the sole reagent either stoichiometrically from inexpensive phenyliodine diacetate or organocatalytically by in situ generation from PhI-mCPBA. In a single step, three C(sp2)-H bonds and one N(sp3)-H bond are functionalized from two different arenes for tandem C-C and C-N bond formation reactions.

Controlled Reactivity of 1,8‐Diazabicyclo[5.4.0]undec‐7‐ene (DBU) in the Selective Synthesis of 1‐(Bromoethynyl)arenes

AbstractThe nucleophilic reactivity of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) was completely controlled by the formation of monohydrate (DBU⋅H2O) in the synthesis of 1‐(bromoethynyl)arenes from 1,1‐dibromoalkenes. Differential reactivity of DBU in protic solvents as compared to aprotic solvents has been explored to prevent the formation of mixtures of products in this reaction. Hydrated DBU is found to be superior to dry DBU, both for the selective synthesis and ease of isolation. In addition, use of DBU⋅H2O as a non‐nucleophilic mild base allowed us to synthesise 1‐(bromoethynyl)arenes via a reaction under solvent‐free conditions. Utilization of DBU⋅H2O as sole reagent also allowed us to isolate the products without column chromatographic purifications.magnified image

Experimental and theoretical investigation of CTAB microemulsion viscosity in the chemical enhanced oil recovery process

Of the most important methods of enhancing oil extraction from petroleum reservoirs includes injecting chemical materials of which surfactants have been found to play a significant role. In surfactant concentrations higher than critical micelle concentration (CMC), formation of micelles is started which will lead to change in the properties of microemulsion. In previous studies, the effect of transformation of micelle from spherical to cylindrical shape on the viscosity of DeAC (dodecyl ammonium chloride) microemulsion has been discussed. In this paper, application of CTAB (Cetyl trimethylammonium bromide, a cationic surfactant) in above CMC ranges has been studied based on the data from laboratory tests and proposed models in order to predict microemulsion viscosity. Moreover, the size of cylindrical micelles has been calculated using some mathematical equations for the first time. The results showed that the shape transformation from spherical to cylindrical happens to CTAB surfactant leading to vigorous increase in viscosity. Additionally, size calculation of micelles in different conditions and their comparison to pore throats dimension of porous media suggest that for certain conditions, they are adequately smaller than the pore throats. It is therefore suggested that CTAB surfactant may be utilized as a sole reagent in lowering IFT and mobility ratio instead of implementation of CTAB-polymer, making the possible chemical enhanced oil recovery (EOR) process less costly.

ChemInform Abstract: Formamides as Lewis Base Catalysts in SN Reactions — Efficient Transformation of Alcohols into Chlorides, Amines, and Ethers.

AbstractA simple formamide catalyst facilitates the efficient transformation of alcohols into alkyl chlorides with benzoyl chloride as the sole reagent.

ChemInform Abstract: Direct Oxidative Lactonization of Alkenoic Acids Mediated Solely by NaIO4: Beyond a Simple Oxidant.

AbstractNaIO4 works not only as an oxidant.

Formamides as Lewis Base Catalysts in SN Reactions-Efficient Transformation of Alcohols into Chlorides, Amines, and Ethers.

A simple formamide catalyst facilitates the efficient transformation of alcohols into alkyl chlorides with benzoyl chloride as the sole reagent. These nucleophilic substitutions proceed through iminium-activated alcohols as intermediates. The novel method, which can be even performed under solvent-free conditions, is distinguished by an excellent functional group tolerance, scalability (>100 g) and waste-balance (E-factor down to 2). Chiral substrates are converted with excellent levels of stereochemical inversion (99 %→≥95 % ee). In a practical one-pot procedure, the primary formed chlorides can be further transformed into amines, azides, ethers, sulfides, and nitriles. The value of the method was demonstrated in straightforward syntheses of the drugs rac-Clopidogrel and S-Fendiline.

ChemInform Abstract: Transition Metal‐Free Amidoalkylation of Benzothiazoles and Amidoalkylarylation of Activated Alkenes with N,N‐Dialkylamides.

A general and practical amidoalkylation reaction, using N,N-dialkylamides in the presence of potassium persulfate as the sole reagent, has been developed. 2-Amidoalkylated benzothiazole- and 3-amidoalkyl-substituted indolinone derivatives were obtained by using benzothiazoles and N-aryl-N-methyl-methacrylamides as substrates, respectively. The transformation proceeded smoothly through amidoalkyl radical intermediates that were trapped by benzothiazoles or activated alkenes.

Transition Metal-Free Amidoalkylation of Benzothiazoles and Amidoalkylarylation of Activated Alkenes with N,N-Dialkylamides.

A general and practical amidoalkylation reaction, using N,N-dialkylamides in the presence of potassium persulfate as the sole reagent, has been developed. 2-Amidoalkylated benzothiazole- and 3-amidoalkyl-substituted indolinone derivatives were obtained by using benzothiazoles and N-aryl-N-methyl-methacrylamides as substrates, respectively. The transformation proceeded smoothly through amidoalkyl radical intermediates that were trapped by benzothiazoles or activated alkenes.

ChemInform Abstract: Deoxygenative Coupling of Nitroarenes for the Synthesis of Aromatic Azo Compounds with CO Using Supported Gold Catalysts.

A facile and efficient catalytic system based on a mesostructured ceria-supported gold (Au/meso-CeO2) catalyst was developed for the synthesis of various aromatic azo compounds by the reductive coupling of the corresponding nitroaromatics, using CO as the sole deoxygenative reagent, under additive-free and mild reaction conditions.

Thiourea sole doping reagent approach for controllable N, S co-doping of pre-synthesized large-sized carbon nanospheres as electrocatalyst for oxygen reduction reaction

The co-doping of heteroatoms into the pre-synthesized graphitic carbons normally requires the use of different doping reagents as heteroatom sources, leading to difficulties in controlling the contents of doped heteroatoms and their chemical bonding forms with graphitic structures. Graphitic carbon-based electrocatalysts with a relatively large size, rich microporous structure and high surface area could possess better structural stability and enhanced conductivity than those of small-sized carbon nanostructures (e.g., nanodots). This study reported the use of a sole reagent (thiourea) as heteroatoms doping source to achieve controllable N, S co-doping of the pre-synthesized graphitic microporous carbon nanospheres (∼100nm in diameter) via a facial thermolysis process to produce high performance oxygen reduction reaction electrocatalysts. Results showed that the contents of the doped N, S and their chemical bonds with graphitic carbon structures could be simply controlled by controlling the thermolysis temperatures. With the experimental conditions investigated, the best performed electrocatalyst was obtained from 1100°C doping process that possessed the most suitable N, S doping contents with 100% of doped N being in electrocatalytically active pyridinic-N and graphitic-N forms. The approach reported in this work could be useful for controllable heteroatoms co-doping of other types of new generation graphitic carbon materials.

ChemInform Abstract: Highly Efficient Synthesis of Azos Catalyzed by the Common Metal Copper (0) Through Oxidative Coupling Reactions.

A facile and efficient approach to synthesize symmetric, asymmetric and bridged aromatic azo compounds (AAzos) from aromatic amines was developed by using red copper as catalyst. Despite numerous efforts towards the catalytic synthesis of symmetric and asymmetric AAzos derivatives, most reactions present certain drawbacks inhibiting their industrial applications, such as laborious multi-step processes, harsh reaction conditions and expensive reagents. And the synthesis of bridged azos had low yields before. With the presence of ammonium bromide as co-catalyst, pyridine as a ligand and molecular dioxygen as a sole oxidative reagent, red copper, a common and abundant metal in nature, exhibited unexpected catalytic activity towards the preparation of AAzos in high yields via one-step reaction, making this catalyst an attractive candidate for industrial and synthetic applications.

Preparation of phenols by phthaloyl peroxide-mediated oxidation of arenes.

This protocol describes an approach to installing hydroxyls into arenes through the direct replacement of C-H bonds with C-O bonds. This direct oxidation avoids the need to prefunctionalize the substrate, use precious metals, introduce directing groups, or use strong Brønsted or Lewis acids. Phthaloyl peroxide, the sole reagent used for this transformation, can be prepared readily from the commodity chemicals phthaloyl chloride and sodium percarbonate. Phthaloyl peroxide oxidizes a diverse range of arenes, and the reactions that involve its use are characterized by high functional group compatibility, which enables the hydroxylation of simple arenes, advanced synthetic intermediates, natural products and other drug-like molecules forming the corresponding phenolic compounds. Notably, the reaction is operationally straightforward and has no special requirements for the exclusion of oxygen and water. The synthesis of phthaloyl peroxide takes 4 h and the subsequent hydroxylation of mesitylene takes 21 h.

A metal-free cross-dehydrogenative coupling of N-carbamoyl tetrahydroisoquinoline by sodium persulfate

A metal-free cross-dehydrogenative coupling of N-carbamoyl tetrahydroisoquinoline with a variety of CH nucleophiles mediated by Na2S2O8 is developed. The reaction proceeds smoothly to give the coupled product in up to 83% yields. The nucleophile scope is broad, including simple ketones, aldehydes, and aryl rings. The carbamoyl protecting group can be readily removed under mild condition. The use of Na2S2O8 as the sole reagent for the CDC reaction is attractive based on economical and environmental factors.

Enantioselective Rearrangement Coupled with Water Addition: Direct Synthesis of Enantiomerically Pure Saturated Carboxylic Acids from α,β‐Unsaturated Aldehydes

AbstractA novel type of organic synthesis enabling a direct one‐pot transformation of α,β‐unsaturated aldehydes into saturated carboxylic acids is described. As sole reagent water is required, which is integrated completely in the product. This tandem process proceeds under perfect atom economy, and consists of two coupled redox biotransformations without the need of external co‐substrates for cofactor regeneration. The initial reduction of the CC double bond of an α,β‐unsaturated aldehyde is catalyzed by an NADPH‐dependent ene reductase, leading to the formation of the saturated aldehyde and NADP+. The aldehyde intermediate is then oxidized to the corresponding carboxylic acid, thus regenerating NADPH for the next catalytic cycle. When using prochiral α,β‐unsaturated aldehydes as substrates the corresponding carboxylic acids are formed enantioselectively with up to >99 % ee as demonstrated, e.g., for the transformation of citral to (S)‐citronellic acid.

Access to Di‐ and Trisubstituted Oxazoles by NBS‐Mediated Oxidative Cyclisation of N‐Acyl Amino Acid Derivatives

AbstractA remarkably simple method for the synthesis of di‐ and trisubstituted functionalised oxazoles under metal‐ and catalyst‐free conditions is described. An iterative bromination and debromination of N‐acylated amino acid derivatives with NBS as the sole reagent cleanly led to various substituted oxazoles.

Direct biocatalytic one-pot-transformation of cyclohexanol with molecular oxygen into ɛ-caprolactone

The development of a biocatalytic process concept for ɛ-caprolactone, which directly converts cyclohexanol as an easily available industrial raw material into the desired ɛ-caprolactone in a one-pot fashion while only requiring air as sole reagent, is reported. The desired product ɛ-caprolactone was obtained with 94–97% conversion when operating at a substrate concentration in the range of 20–60mM. At higher substrate concentrations, however, a significant drop of conversion was found. Subsequent detailed studies on the impact of the starting material, intermediate and product components revealed a significant inhibition and partial deactivation of the BVMO by the product ɛ-caprolactone (in particular at higher concentrations) as well as an inhibition of the BVMO by cyclohexanol and cyclohexanone.

Value Of Skin Testing Solely With Penicillin G In Children With a History Of Penicillin Allergy

For most part of the last decade, PrePen® has been unavailable commercially. This situation has compromised the evaluation of many patients with a history of penicillin allergy. During this period, evaluation of children with a history of penicillin allergy continued in our center using penicillin G as the sole reagent for skin testing. We aimed to determine the negative predictive value and safety of this approach. We reviewed the files of all patients evaluated for a history of penicillin allergy between December 2006 and December 2009 at the CHU Sainte-Justine Allergy Clinic. Evaluation consisted of skin testing with penicillin G 10,000 IU/mL followed if negative by a graded challenge to the culprit penicillin. We evaluated 563 patients during this period. Among these, 185 (32.9%) had a positive skin test to penicillin G and 378 (67.1%) had a negative skin test. A reaction occurred in 4.8% (18/375) of patients following challenge. Three patients were not challenged. All reactions were mild and generally limited to the skin. The negative predictive value of skin testing solely with penicillin G was calculated at 95.2% (92.5-97.1%). This study raises questions about the relevance of skin testing children with a history of penicillin allergy with a large array of skin test reagents as the negative predictive value of penicillin G alone approximates that of the recommended approach. Also, it offers support for a simpler and safe alternative to skin testing in these children using penicillin G as the sole skin test reagent.