Search

[Display omitted] Syntheses of new ferrocenyl-containing tertiary alcohols derived from l-proline were developed. In these alcohols,two ferrocenyl groups are bonded at prolinol moiety directly or through p -phenylene spacer. Specific features for the ferrocene Grignard reagents were discovered. [ABSTRACT FROM AUTHOR]

[Display omitted] In response to rising environmental concerns, chemistry is experiencing a considerable change in both concepts and practices to adopt more efficient and sustainable technologies. One of the alternative technologies that offer many advantages over the conventional solution-based techniques is mechanochemistry which utilizes mechanical energy to induce chemical reactions. Despite the fact that mechanochemistry has reached high significance in the creation of advanced materials, such as alloys, ceramics, electrode materials, and nanocomposites, in the field of small molecule synthesis its potential remains largely untapped. This review highlights the opportunities and prospects of different mechanochemical tools in the synthesis of organometallic compounds, including transition metal complexes with N-heterocyclic carbene, arene, and cyclopentadienyl ligands, monometallacyclic and pincer derivatives, as well as main group metal compounds (e.g. , allyl complexes and the Grignard reagents). Many important organometallic transformations such as C–H bond metalation, transmetalation, and oxidative addition can be successfully implemented under mechanochemical conditions in a highly productive and energy-saving manner. Furthermore, the postmodification of metal-containing species upon grinding or milling is shown to be a powerful route to both new discrete metal complexes and different supramolecular architectures (metal-containing organic cages, macrocylces, networks). [ABSTRACT FROM AUTHOR]

[Display omitted] Efficient synthesis of ionic liquids based on stereoisomerically pure natural and synthetic higher (5 Z ,9 Z)-alkadienoic acids and choline hydroxide was developed. The key unsaturated carboxylic acids were prepared using the stereoselective cross-cyclomagnesiation reaction of aliphatic and oxygen-containing 1,2-dienes with EtMgBr in the presence of Mg metal and Cp 2 TiCl 2 catalyst. [ABSTRACT FROM AUTHOR]

• Lanthanoid pseuo-Grignard reagents. • Lanthanoid Chemistry. • Reactivity of lanthanoid organometallic compounds. • Interactions of RLnX with organic substrates. This review covers the progress of the chemistry of divalent lanthanoid pseudo-Grignard, compounds, with E-Ln-X bonding (E = C, N, O; X = I, Br, Cl, F), especially since the 2002 review of Petrov et al. (2002)[1]. Emphasis is on synthetic pathways and the structures of these compounds. Their use in oxidation and metathesis reactions is discussed together with a consideration of interactions with organic substrates. The compounds appear to have considerable untapped potential. This review covers the progress of the chemistry of divalent lanthanoid pseudo-Grignard, compounds, E-LnX (E = C, N, O; X = I, Br, Cl, F). Emphasis is on synthetic pathways, structures and reactivity of these compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

• The first structural authentication of a menthylmagnesium compound is reported. • In solution epimerization occurs leading to mixtures of menthyl- and neomenthylmagnesium complexes. • Mg-bound menthyl and neomenthyl groups exhibit significantly different nucleophilicity allowing the synthesis of enantiomerically pure phosphane sulfides via a metathetical approach. 1,4-Dioxane (dx) reacts with the well-known Grignard reagent, prepared via reduction of (-)-menthyl chloride with magnesium in diethyl ether, to a mixture of the three diastereomeric magnesium compounds R 2 Mg(dx) x , R' 2 Mg(dx) x and RR'Mg(dx) x (R = (1R)-menthyl and R' = (1S)-neomenthyl). Addition of N,N,N',N' -tetramethylethylenediamine (TMEDA) to this solution yields (tmeda)Mg(R/R') 2 (R : R' ≈ 3 : 1) (1) via substitution of ligated dx ligands. The reaction of (R/R') 2 Mg(dx) x with diphenylchlorophosphane (molar ratio 1 : 1) in diethyl ether at a temperature regime of 0 °C to reflux and subsequent oxidation with elemental sulfur leads to formation of pure (-)-menthyldiphenylphosphane sulfide RPh 2 P(S) (2). Compounds 1 and 2 have been authenticated by X-ray crystal structures determinations. [Display omitted] [ABSTRACT FROM AUTHOR]

Grignard reagents can provide a simple path to generate, through their thermal decomposition, magnesium (Mg) and/or its hydride (MgH 2). However, existing compounds lack the ability to lead to "adequate" MgH 2 structures to enable effective hydrogen storage. Herein, we report on the possibility to tune Grignard reagent's chemical structure, i.e. number of β-hydrogen, and the activation energy for their thermal decomposition to lead to Mg/MgH 2. For example, di- tert -butylmagnesium with nine β-hydrogen was able to decompose at a very low temperature of 167 °C to generate MgH 2 /Mg, which is 100 °C lower than the temperature required to generate MgH 2 from di- n -butylmagnesium, i.e. the only compound known to date. More remarkably, the MgH 2 synthesized from the di- tert -butylmagnesium precursor was able to release hydrogen from 100 °C. These promising hydrogen storage properties are credited to the formation of the metastable γ-MgH 2 phase, which is believed to result from the structural defects generated upon the thermal decomposition of di- tert -butylmagnesium. The stereochemistry and carbon chain length of the Grignard reagents can be tuned to prepare MgH 2 nanoparticles of different morphology, sizes, and structures. [Display omitted] • Thermolysis of Grignard reagents provides a simple path to prepare nanosized MgH 2. • The number of β-hydrogen in the precursor is a significant parameter in this process. • Grignard reagents with a higher activation energy led to smaller MgH 2 nanostructures. • Di- tert -butylmagnesium (t -bu 2 Mg) had the lowest decomposition temperature. • t -bu 2 Mg led to the formation of γ-MgH 2 and appears to be the most promising precursor. [ABSTRACT FROM AUTHOR]

The synthesis of Grignard reagents, which are formed by the reaction of magnesium and organic halides (RX), is hazardous because of the highly exothermic nature of this reaction. In this work, calorimetry and infrared (IR) spectroscopy were used to identify the exothermic mechanism and process hazards for the synthesis of n -butylmagnesium bromide Grignard reagent (n -BuMgBr) in diethyl ether (DE), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), cyclopentylmethyl ether (CPME), and diethylene glycol butyl ether (DGBE). The latter three solvents were chosen by the substitution principle of the "inherent safety" design concept, which aims to reduce the risk of the target reaction in a fundamental manner. An EasyMax102 calorimeter was used to characterize the exothermic behavior of the reactions using isothermal and isoperibolic experiments carried out in a semi-batch glass reactor coupled with an IR probe to monitor changes in the species and concentrations during the reaction process. An adiabatic TAC-500A calorimeter was also used to understand the adiabatic decomposition behavior of the products obtained in the isothermal experiments under the worst-case (cooling failure and thermal runaway) scenario. Meanwhile, density functional theory calculations were performed to understand the reaction pathway and associated energies based on the experimental data. Further, the risk assessment of thermal runaway was analyzed using a risk matrix and a Stoessel criticality diagram. The results indicate that the risk of the reactions when using 2-MeTHF, CPME, and DGBE are all class 1, making reactions in these solvents inherently safer than those using DE or THF, which were both class-3 risks. These findings provide further evidence that 2-MeTHF, CPME, and DGBE are safer than the typical solvents used for the industrial production of Grignard reagents. [ABSTRACT FROM AUTHOR]

[Display omitted] Treatment of 2,4-alkadienyl carboxylates with an aryl Grignard reagent in the presence of a catalytic amount of FeCl 2 affords diene derivatives in high yields with regio- and cis -stereoselectivity. Additionally, optically active 2,4-alkadienyl carboxylates afford the corresponding optically active dienes in high yields and with excellent degrees of chiral transfer. More importantly, the absolute structures of both starting material and product clarified the stereochemical pathway. [ABSTRACT FROM AUTHOR]

[Display omitted] Herein, we report the regio- and stereoselective nucleophilic addition reactions of Swaminathan ketone 2a and its methylated analog 2b , both of which contain a 6–7 fused carbocyclic enedione moiety. Nucleophilic additions to 2 using generic organometallic reagents, such as Grignard and organolithium reagents, preferentially occurs at the conjugated carbonyl group to afford a range of tert -alcohols with high stereoselectivity. The selectivity observed with 2 was notable when compared to that observed with Wieland–Miescher ketone 1a bearing a decalin framework. A variety of substituents, such as alkyl, alkenyl, alkynyl and aryl groups, can be introduced into 2 using this method. Exceptionally, the allylation reaction of 2 occurred at both the conjugated and non-conjugated carbonyl groups, but this regioselectivity problem was solved using organocopper reagents. [ABSTRACT FROM AUTHOR]

[Display omitted] • The high-density 3D MFCs with optimized channels and volumes were designed using femtosecond laser technology. • The Barker's transformation ensured fast and efficient gas–liquid mass transfer. • Grignard reagents were produced at room temperature on demand and rapidly converted. • The conversion of CO 2 into value-added chemicals were completed within 40 s. • The space–time yield was much higher than batch reactors. Efficient conversion of low reactive CO 2 within a short residence time of flow chemistry presents a challenge. We have tackled this issue by developing 3D microfluidic chips (MFCs) with high-density, small-diameter, and large-volume for CO 2 gas–liquid reactions using femtosecond laser technology. Our innovative design effectively shortens reaction times while satisfying the required temperature and pressure conditions. One of the key features is the integration of the 3D Barker's transform structure, which provides an efficient gas–liquid contact area for mass and heat transfer, even at low Reynolds numbers. As a proof of concept, we synthesize 2,4,5-trifluorobenzoic acid and various other fluorinated carboxylic acids in 3D MFCs using Grignard reagents and CO 2. Impressively, the Grignard reagents can be generated in situ and utilized at room temperature, and the CO 2 carboxylation reaction with 3D MFCs takes only 40 s with a yield of 97 %. Our findings highlight the feasibility of this multifunctional, efficient, and fast CO 2 flow conversion process, providing a valuable tool to produce value-added chemicals via 3D MFCs techniques. [ABSTRACT FROM AUTHOR]

• Treatment of 2,6-dimethyl-3,5-dicarboethoxy-4-(2-methoxyphenyl)-1,4-dihydropyridine (1) with i -PrMgBr, followed by D 2 O, workup, and recrystallization gave the starting dihydropyridine 1. NMR analysis of product indicated that no metalation had occurred at the C-2 and C-6 methyl positions (no deuterium incorporation at the C-2 and C-6 methyl positions and any other position in the molecule). Moreover, no addition products resulting from nucleophilic attack of Grignard reagent at either or both of the ester groups of 1 were observed. As a result, ester groups are tolerated and i -PrMgBr cannot be used as a strong base for C-deprotonation of classical Hantzsch esters. • Treatment of 2-bromomethyl-1,4-dihydropyridine derivative 2 with i -PrMgBr Grignard reagent at mild reaction condition furnished the organomagnesium reagents of Hantzsch esters through the halogen-magnesium exchange reaction with ester groups tolerance. • Trapping the magnesiated 1,4-dihydropyridine 2 with hard electrophile methyl iodide gave the major N-methylated product 6 and minor pyridine derivative 7. • In trapping the magnesiated reaction mixture with ethyl bromide, pyridine derivative 8 (15%) and dimer 9 (20%) could be separated. • N-Methylated product 6 and dimer 9 could be obtained through the intermediacy of dimagnesiated spiece 3. • The aromatization of dihydropyridine ring and formation of pyridine derivatives 7 and 8 could be occurred through the hydrolysis of organomagnesium derivative 5 or reaction of it with EtBr electrophile, respectively. • Iron-catalyzed cross-coupling reaction of 2 with allylMgBr, i -PrMgBr, and n-BuMgBr Grignard reagents afforded unsymmetrical 1,4-dihydropyridine Hantzch esters 10a-c in good yields. • Since the presence of N H bond of Hantzsch dihydropyridines is essential for the pharmaceutical effects of this class of compounds, thus, by using of this procedure, it is possible to prepare unsymmetrical 1,4-DHPs without protecting the N H group. The mild bromine-magnesium exchange reaction using i -PrMgBr in THF on the 2-bromomethyl-1,4-dihydropyridine Hantzsch esters allowed the synthesis of highly functionalized magnesiated 1,4-dihydropyridines with ester groups tolerance. Treatment of the resulting anionic intermediates with hard electrophile methyl iodide gave N-methylated product 6 and pyridine derivative 7 in 60 % and 10 % yields, respectively. In trapping the reaction mixture of magnesiated 1,4-dihydropyridine with ethyl bromide, pyridine derivative 8 , and dimer 9 were obtained. Also, FeCl 3 -catalyzed cross-coupling reaction of allylMgBr, i -PrMgBr, and n -BuMgBr Grignard reagents with 2-bromomethyl-1,4-dihydropyridine derivative 2 afforded unsymmetrical 1,4-dihydropyridine derivatives 10a-c in good yields. [Display omitted] [ABSTRACT FROM AUTHOR]

• Silylation of partially fluorinated epoxides at ambient temperature using Grignard reagent. • Stabilizing effect of oxiranyl anions by fluoroalkyl group. The reaction of partially fluorinated epoxides with strong, hindered bases in the presence of electrophiles resulted in functionalization of the epoxy ring. For example, the reaction of hexafluoroisobutene epoxide with LDA and trimethyl- or triethychlorosilanes at low temperature led to the formation of the corresponding epoxy silanes. In the case of the E- and Z-epoxides of 1,1,1,3,3,3-hexafluorobutene-2, the deprotonation step can be successfully carried out using i-PrMgCl.LiCl (Turbo Grignard reagent), and the reaction with chlorosilanes can be carried out at ambient temperature, which significantly simplifies the synthetic protocol. The process was found to be stereospecific, proceeding with complete retention of configuration of the epoxide ring and giving access to pure E- or Z- isomers of the corresponding epoxy silanes. Using this protocol, the corresponding epoxy silanes were also prepared from the epoxides of E- 3,3,3,1-tetrafluoropropene-1 and 3,3,3-trifluoropropene-1. The new silanes were demonstrated to be convenient reagents for the transfer of a fluorinated epoxy moiety to carbonyl compounds under fluoride anion catalysis. This process was shown to proceed with complete retention of the geometry of the epoxy ring. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel cyclic molecular designed dispersion (CMDD) method was employed to uniformly deposit 0.0–6.5 wt% Fe on CeO 2. The gold catalysts (0.0–3.8 wt%) supported on Fe 2 O 3 -CeO 2 were tested for CO preferential oxidation (PROX). As the CMDD method involved grafting of Fe (acac) 3 onto the surface –OH groups, 2.7 surface –OH/nm2 was determined for the CeO 2 by using the Grignard reagent. The performance of CMDD catalysts was compared with the corresponding catalysts prepared by impregnation. The catalysts were characterized by XPS, XRD, TPR, HRTEM-EDX, BET and ICP. The results suggested that Au/Fe 2 O 3 -CeO 2 was significantly more active and selective than Au/CeO 2. The CMDD-prepared catalysts with 1.4–2.5 wt% iron showed the highest activity and selectivity, especially at temperatures as low as 323 K. The formation of Ce-Fe solid solution for CMDD catalysts promoted the dispersion of both iron and gold. Highly dispersed gold nanoparticles mainly as small as 2.2 nm were observed in HRTEM. Image 1 • Cyclic molecular designed dispersion (CMDD) method was used to graft Fe 2 O 3 on CeO 2. • CMDD of Fe 2 O 3 enhanced iron dispersion and its interaction with Au and CeO 2. • CMDD PROX catalysts are more active and selective than impregnation ones. • An Au/Fe ratio of about 0.4 on CeO 2 reduces complete oxidation of CO to 318 K. • Highly dispersed nanosized gold particles with diameter of 1–3 nm were achieved. [ABSTRACT FROM AUTHOR]

[Display omitted] 21,21,21-Trifluoro(aryl)thevinols were synthesized by the reaction of 21,21,21-trifluorothevinone with aryl Grignard reagents. The absolute configuration at C20 atom in these CF 3 -substituted alcohols can be easily determined by one-dimensional 19F NMR spectroscopy that was verified by X-ray diffraction studies. [ABSTRACT FROM AUTHOR]

A convenient access to 2-hydroxycyclopentenones was designed from acylcyanohydrins, by using titanacyclopropane complexes as nucleophilic partners and an intramolecular aldol condensation in basic conditions. The development of a one-pot procedure allows a step- and atom-economic process, and the use of Grignard reagents other than ethylmagnesium bromide provided valuable 3,4-disubstituted 2-hydroxycyclopentenones. The utility of the hydroxy group was illustrated by further functionalization of the α-position using palladium-mediated cross-coupling reactions. Image 1 • Original substituted 2-hydroxycyclopentenones.. • Titanacyclopropane complexes. [ABSTRACT FROM AUTHOR]

Malononitriles are valuable synthetic intermediates for many applications, including the synthesis of herbicides and other biologically active molecules, and the synthesis of chiral ligands for asymmetric catalysis. This article describes the development of a procedure for the conversion of primary nitriles to malononitriles using dimethylmalononitrile, a commercial, non-toxic, carbon-bound source of electrophilic cyanide. This procedure avoids the use of toxic cyanide or malononitrile as a starting material. This protocol is further applied to the dicyanation of benzyl Grignard reagents, generated from benzyl bromides, yielding fully functionalized malononitriles from a nitrile-free precursor. Image 1 [ABSTRACT FROM AUTHOR]

• Approach to sesquiterpenoids with trimethyl(p -tolyl)cyclopentanes is reported. • Stork-Danheiser sequence on vinylogous ester yileds 3-arylcyclopetenone 11a. • α-Methylation of enone 11a sets all carbon present in Laurokamurene B (1b). • (±)-Laurokamurene B (1b) is synthesized in 5 steps with 45.4% overall yield. A unified approach to the sesquiterpenoids sharing common trimethyl(p -tolyl) cyclopentane skeleton has been disclosed via a key Stork-Danheiser sequence on a cyclopentane based vinylogous ester with aryl Grignard reagent followed by α-methylation strategy. The strategy is eventually applied to the concise formal total synthesis of (±)-laurokamurene B (1b) in only 5 steps with 45.4% overall yield. [ABSTRACT FROM AUTHOR]

A series of BR 2 complexes of α -pyrrolyl dipyrrin were synthesized from BF 2 complex of α -pyrrolyl dipyrrin (3-pyrrolyl BODIPY) by treating it with various alkyl- and aryl magnesium halides under mild Grignard reaction conditions. The BR 2 complexes were functionalized at α -position of the appended pyrrole ring with formyl, chloro and bromo functional groups and these functionalized BR 2 complexes were used further to prepare various novel derivatives of BR 2 complexes. The BR 2 complexes were characterized by HR mass, NMR, absorption, fluorescence, and electrochemical techniques. Two of the BR 2 complexes were structurally characterized by X-ray crystallography. Our studies revealed that the substitution of fluorine atoms at the boron center of 3-pyrrolyl BODIPYs with different alkyl/aryl groups significantly alters their structural, spectral and electrochemical properties. The DFT studies also support the alteration of the electronic properties of the BR 2 complexes. Image 1 [ABSTRACT FROM AUTHOR]

Conditions: (a) i -PrMgCl·LiCl, THF, −10 °C, 30 min. (b) N,N'-carbonyldiimidazole, THF, r.t., 1 h. (c) THF, −10 °C to r.t., 3 h. • Synthesis of 2-acyl benzothiazoles/thiazoles from various carboxylic acids. • Appropriate for Boc-protected amino acids and dipeptide. • Moderate to excellent yields under mild reaction conditions. A convenient and efficient strategy for the synthesis of 2-acyl benzothiazoles/thiazoles has been developed. The treatment of benzothiazole/thiazole with allylic Grignard reagents readily generates the corresponding 2-Grignard reagents, which is followed by a reaction with N,N'-carbonyldiimidazole activated carboxylic acids to afford various 2-acyl benzothiazoles/thiazoles products. The synthetic method is applicable to a wide array of carboxylic acids and allows easy access to 2-acyl benzothiazoles/thiazoles with considerable yields under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Development of enantioselective synthesis of precursor en route to paxilline indoloterpenoids is described. Evaluation of 25 diphosphine-based ligands has led to identification of JosiPhos derivative that allows for asymmetric conjugate addition of homoprenyl Grignard reagent to 2-methylcyclopent-2-en-1-one in excellent yield and with appreciable levels of enantioinduction. Application to the conjugate addition of other Grignard reagents is demonstrated. Image 1 [ABSTRACT FROM AUTHOR]

A concise, unified and stereoselective total synthesis of (+)-gabosine C and (+)-4- epi -gabosine J from a common polyhydroxylated cyclohexenol intermediate which was synthesized from readily available D-ribose has been described. The synthetic avenue includes stereoselective Grignard reaction, silyl ether deprotection followed by acetate migration, RCM reaction, oxidative diol cleavage, hydroxymethylation and oxidative rearrangement as key steps. Image 1 • Asymmetric total synthesis of (+)-Gabosine C and (+)-4- epi -Gabosine J from a common intermediate. • Deprotection followed by acetate group migration, RCM reaction and oxidative rearrangement reaction as key steps. • Functionalisation of common intermediate to carbasugars. [ABSTRACT FROM AUTHOR]

• C H bond functionalization. • Cross-dehydrogenative coupling (CDC). • Grignard reaction. C H bond functionalization for C N and C C bond formations via cross-dehydrogenative coupling (CDC) of N -allylbenzamides with indole as amine source has been developed under a copper-catalyzed condition. To the best of our knowledge, these are the first examples in which different classes of N -containing compounds were directly prepared from the readily available N -allylbenzamides using an inexpensive catalyst-oxidant (CuSO 4 /TBHP) system. Further, it was applied for the synthesis of α-substituted N -allylbenzamides by using Grignard reagent as nucleophiles. [ABSTRACT FROM AUTHOR]

Abstract An efficient, versatile, enantioselective synthesis of 1,3-disubstituted and 1,3,6-trisubstituted 5-methylidenedihydrouracils applying Horner-Wadsworth Emmons methodology was developed. Starting 1,3-disubstituted 5-diethoxyphosphoryluracils were subjected to reduction of the double bond or addition of various Grignard reagents and obtained Horner-Wadsworth Emmons reagents were used for the olefination of formaldehyde. Enantioselective synthesis of 1,3,6-trisubstituted 5-methylidenedihydrouracils was accomplished by introducing (R , R)- or (S , S)-di(1-phenylethylamino)phosphoryl groups as chiral auxiliary. Additions of Grignard reagents in the presence of these groups were highly and complimentary diastereoselective (de ∼ 80%). Further separation of the diastereomeric mixtures by column chromatography enabled synthesis of (R)- and (S)-1,3,6-trisubstituted-5-methylidenedihydrouracils with ee ≥ 98%. Furthermore, absolute configuration of the adducts and final products was established using single crystal X-ray analysis. Stereochemical course of the addition reactions is also discussed. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract The reaction of organolithium and Grignard reagents with pentacarbonyl[(ethoxy)(2-phenylethenyl)carbene]chromium(0) gave, after the quenching of the initially formed product of the 1,4-addition, different products depending on the organometallic and quenching reagents used. The addition of organolithiums, followed by a work-up with acid (AcOH or HCl), afforded the corresponding carbene complexes. In contrast, quenching the reaction mixture with ethanol led to the stereoselective formation of (Z)-enol ethers. The usage of Grignard reagents led to the formation of the carbene complexes regardless of which quenching reagent was used. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A strictly ordered combination of three different units is attained in one flask. • Iron and copper play complementary roles to determine the structure of olefins. • Iron leads environmentally friendly and economical synthesis of valuable compounds. • Superior production of a single isomer among possible five is artificially realized. Abstract Iron-catalyzed δ-selective conjugate addition of methyl and cyclopropyl Grignard reagents to α,β,γ,δ-unsaturated esters and amides took place in good yields to give products exclusively with cis -β,γ-olefinic bond. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • CYP24A1 metabolites of 25-hydroxyvitamin D 3 were efficiently synthesized. • The Claisen condensation was used for the 23,25-dihydroxyvitamin D 3 metabolite. • 23,25,26-Trihydroxyvitamin D 3 was synthesized using Grignard reaction. Abstract Three 23-hydroxylated vitamin D 3 derivatives, which are metabolites of 25-hydroxyvitamin D 3 produced by CYP24A1 and a related diastereomer, were efficiently synthesized. Each C23 hydroxy unit was constructed by the Claisen condensation reaction with ethyl acetate or the Grignard reaction with 2-methylallymagnesium chloride. Stereochemistry at the C23 position was determined by a modified Mosher's method. The triene structures were constructed by the Wittig-Horner reaction utilizing the A-ring phosphine oxide moiety. [ABSTRACT FROM AUTHOR]

Abstract Owing to the unusual reactivity of dialkylamine-borane complexes, a methodology was developed to simply access boronic acids. The intrinsic instability of magnesium aminoborohydride was tweaked into a tandem dehydrogenation borylation sequence. Proceeding via an autocatalytic cycle, amineborane dehydrogenation was induced by a variety of Grignard reagents. Overall, addition of the organomagnesium species onto specially designed dialkylamine-borane complexes led to a variety of boronic acids in high yields. In addition, the reaction can be performed under Barbier conditions, on a large scale. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Simple synthesis of optically active N , O -protected derivatives of 4,4-difluoroglutamic acid. • The application of copper complex formed from Cu/BrCF 2 CO 2 Et/TMEDA in ring opening reactions. • Copper catalyzed 1,4-addition of pentafluoroarylmagnesium chloride to dehydroalanines. Abstract Ring opening reactions of 1 with copper complex formed between Cu, TMEDA and BrCF 2 CO 2 Et lead to optically active 4,4-difluoroglutamic acid derivatives 11a-d in moderate yields. Reaction of cyclic sulfamidates 1 with fluoro substituted arylmagnesium chlorides proceed via copper catalyzed 1,4-addition of Grignard reagent to dehydroalanine 2 , formed in situ. Fluorinated organoznic derivatives were unreactive towards 1 regardless of the reaction conditions; instead product of reaction of 1 with DMF was isolated. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract (5a R)-5a- C -pentyl-4- epi -isofagomine 1 is a powerful inhibitor of lysosomal β-galactosidase and a remarkable chaperone for mutations associated with GM1-gangliosidosis and Morquio disease type B. We report herein an improved synthesis of this compound and analogs (5a- C -methyl, pentyl, nonyl and phenylethyl derivatives), and a crystal structure of a synthetic intermediate that confirms its configuration resulting from the addition of a Grignard reagent. These compounds were evaluated as glycosidase inhibitors and their potential as chaperones for mutant lysosomal galactosidases determined. Based on these results and on docking studies, the 5- C -pentyl derivative 1 was selected as the optimal structure for further investigations: this compound induces the maturation of mutated β-galactosidase in fibroblasts of a GM1-gangliosidosis patient and promote the decrease of keratan sulfate and oligosaccharide load in patient cells. Compound 1 is clearly capable of restoring β-galactosidase activity and of promoting maturation of the protein, which should result in significant clinical benefit. These properties strongly support the development of compound 1 for the treatment of GM1-gangliosidosis and Morquio disease type B patients harboring β-galactosidase mutations sensitive to pharmacological chaperoning. [ABSTRACT FROM AUTHOR]

Abstract A Grignard reagent containing pyrene, 1-pyrenylmethylmagnesium bromide (PMgBr), was explored as a novel reactive compatibilizer for producing aliphatic polyketone (PK) composites with multi-walled carbon nanotube (MWCNT) that had improved interfacial adhesion and mechanical strength. 1-Bromomethylpyrene (PBr) was adsorbed on MWCNTs and reacted with Mg to produce PMgBr on MWCNTs (MWCNT-PMgBr). PK-grafted MWCNT (PK-g-MWCNT) was prepared by reacting MWCNT-PMgBr with PK, and its composite with PK was fabricated by melt extrusion. The formation of PK-g-MWCNT was examined by spectroscopy, electron microscopy, and thermal analysis. The PK interfacial adhesion energies with MWCNTs were quantified, and the mechanical strengths of their composites examined. PK-g-MWCNT had the highest interfacial adhesion energy with PK among the MWCNTs. The PK/PK-g-MWCNT composite showed better MWCNT dispersion in PK and interfacial adhesion between MWCNT and PK than the PK/pristine MWCNT composite. Consequently, the PK/PK-g-MWCNT composite exhibited higher mechanical strength than the PK/pristine MWCNT composite when the composite contained the same amount of MWCNTs. [ABSTRACT FROM AUTHOR]

Synthetic analogues of natural 5Z,9Z-dienoic acids - hybrid molecules based on the oximes of cholesterol, pregnenolone, and androsterone with 1,14-tetradeca-5Z,9Z-dienedicarboxylic acid - were synthesized for the first time and studied for antitumor activity in vitro . The acid was prepared using catalytic cyclomagnesiation of O-containing 1,2-dienes with Grignard reagent in the presence of Cp 2 TiCl 2 as the key step. Using flow cytometry, it was shown for the first time that the new molecules are efficient apoptosis inducers in the HeLa, Hek293, U937, Jurkat, and K562. [ABSTRACT FROM AUTHOR]

NF00659B 1 is a novel α-pyrone diterpenoid natural product with potent anti-colon cancer activity. A stereoselective approach to the 2,2-dimethyl oxepanol core of NF00659B 1 is described enlisting a sequence of olefinic ester ring-closing metathesis, epoxidation, and Grignard addition. This strategy paves the way to a total synthesis of NF00659B 1 for further biological studies. [ABSTRACT FROM AUTHOR]

[Display omitted] The total synthesis of the natural (8 E ,15 E ,22 E)-heptatriaconta-8,15,22-trien-2-one and (15 E ,22 E)-heptatriaconta-15,22-dien-2-one is reported. Our synthesis involved a modular and convergent approach, based on the copper-catalyzed addition of Grignard reagents to allylic olefins. The obtention of these methyl ketones is an important asset for the use of these compounds as analytical patterns with application in Earth sciences. [ABSTRACT FROM AUTHOR]

• We explore here the products of the reaction of the Grignard reagent t -BuMgCl with AlCl 3 (1:1) in THF, and how their presence in solutions affect their electrochemical behavior. • Two complex products were isolated from the precipitated part of the reaction and the counter solution part, which exhibit two distinct single-crystal structures. • Crystallization from precipitated part (compound I) has the molecular structure [MgCl·THF 5 ]+ [AlCl 4 ]– and it is electrochemically inactive in terms of reversible Mg dissolution/deposition. • The molecular structure of the second compound (II) , obtained from solution part is [Mg 2 (μ-Cl) 3 ·THF 6 ]+ [ t -BuAlCl 3 ]- and its solutions in THF exhibit reversible Mg dissolution/deposition behavior. • This study demonstrates the possibility of tuning judiciously the electrochemical response of ethereal solutions of magnesium organohaloaluminate complexes through their structural modifications. The electrochemical response of ethereal solutions containing magnesium organohaloaluminate complexes has drawn great interest in recent decades owing to their relevance to rechargeable magnesium batteries, as demonstrated with solutions containing complexes formed by reacting R 2 Mg and AlCl 2 R moieties in ethers like tetrahydrofuran (THF). However, most of previous reports focused on battery related performances, and less on the structure of the active species. Herein, we focus on (1) identifying electroactive species and (2) correlating the electrochemical properties of their solutions to the preparation modes: either through reactions of their precursors in THF, or by dissolving isolated crystallized products in the ether solvent. Specifically, we explore the products of the reaction of the Grignard reagent t -BuMgCl with AlCl 3 (1:1) in THF, and how their presence in solutions affect their electrochemical behavior. We isolated two complex products, one non-soluble and one soluble in THF, which exhibit two distinct single-crystal structures. The molecular structure of the two complexes obtained from the single-crystal X-ray diffraction (SCXRD) and nuclear magnetic resonance (NMR) measurements was correlated with the electrochemical behavior of their solutions in THF, as reflected by their cyclic voltammetry (CV) response. We found that one product (compound I) has the molecular structure [MgCl·THF 5 ]+ [AlCl 4 ]– and it is electrochemically inactive in terms of reversible Mg dissolution/deposition. The molecular structure of the second compound (II), [Mg 2 (μ-Cl) 3 ·THF 6 ]+ [ t -BuAlCl 3 ]–, has not been reported before, and its solutions in THF exhibit reversible Mg dissolution/deposition behavior. Our study clearly demonstrates the possibility of tuning judiciously the electrochemical response of ethereal solutions of magnesium organohaloaluminate complexes through their structural modifications. [Display omitted] [ABSTRACT FROM AUTHOR]

A method for generating alkynylmagnesium chlorides from 1-chlorovinyl p -tolyl sulfoxides and an isopropylmagnesium chloride–lithium chloride complex (turbo Grignard reagent) has been developed. The method consists of a sulfoxide/magnesium exchange reaction of 1-chlorovinyl p -tolyl sulfoxides and a turbo Grignard reagent, a Fritsch–Buttenberg–Wiechell rearrangement of the resulting magnesium alkylidene carbenoids, and a deprotonation of terminal alkynes with a turbo Grignard reagent. The resulting alkynylmagnesium chlorides are reacted with a variety of electrophiles to generate internal alkynes. [Display omitted] [ABSTRACT FROM AUTHOR]

The reactions of bis-(bromomagnesiummethyl)carboranes with dimethyldimethoxysilane were studied. It has been shown that interaction of 1,2-bis-(bromomagnesium)- o -carborane with an excess of dimethyldimethoxysilane gives the mixture of 1,2-(methoxydimethylsilylmethyl)- o -carborane and exocyclic 1,2-( o -carboranyleno)-4,6-bis-(dimethylsilyl)-5-oxa-cycloheptane. In the case of 1,7-bis-(bromomagnesiummethyl)- m -carborane, only 1,7-bis-(methoxydimethyl-silylmethyl)- m -carborane is formed. The possibility of obtaining Grignard reagents from 1,2 (7)-(bromomethyl)- o(m) -carboranes has been established. [ABSTRACT FROM AUTHOR]

A series of novel pyrido[2,3- d ]pyrimidine derivatives 6 were prepared starting from 2-amino-3-cyano-4-trifluoromethyl-6-phenyl pyridine 3 via Grignard’s reaction, cyclization followed by coupling with aliphatic and cyclic amines. All the compounds 6 were screened for antibacterial, minimum bactericidal concentration (MBC), biofilm inhibition activity as well as antifungal and minimum fungicidal concentration (MFC) activities. Among the screened compounds, the compounds 6e , 6f , and 6m which showed exhibiting promising activity have been identified. The results reveal that the compound pyrido[2,3- d ]pyrimidine derivative 6e altered the sterol profile which may exert its antifungal activity through inhibition of ergosterol biosynthesis and could be an ideal candidate for antifungal therapy. The molecular docking results also validated the antifungal results. [ABSTRACT FROM AUTHOR]

Compounds [2-(Et 2 NCH 2 )C 6 H 4 ] 2 SbX [X = Cl ( 1 ), Br ( 2 )] and [2-( i -Pr 2 NCH 2 )C 6 H 4 ] 2 EBr [E = Sb ( 3 ), Bi ( 4 )] were prepared by coupling reactions between organolithium derivatives or Grignard reagents and the corresponding metal halides. Compounds 1 – 4 were characterized in solution by multinuclear NMR spectroscopy, mass spectrometry and their molecular structures were determined by single-crystal X-ray diffraction. The coordination geometry around the metal centers is square pyramidal in 1 and 2 , and see-saw in 3 and 4 . [ABSTRACT FROM AUTHOR]

The application of NF membranes is still a big challenge because of both organic and inorganic fouling. In our previous studies, we have clearly shown that grafting of TiO 2 NF membranes with organic groups, and especially grafting with methyl groups using Grignard reagents, leads to a strong antifouling effect for different organic materials. In this paper, we study the irreversible fouling of inorganic foulants such as iron and manganese hydroxides/oxides/salts (scaling) of native and grafted ceramic NF membranes. In addition, the influence of the presence of organics on inorganic fouling and co-effects of multiple organic materials (e.g. humic acids and alginate) on the fouling were also measured. As a final test, the potential of the surface grafted ceramic NF membranes is also evaluated in real surface water, where many different foulants are present simultaneously. In all cases, the strong antifouling effect of methyl Grignard grafting is confirmed. For the investigated membranes with varying amount of polar surface groups, humic acids decrease the fouling tendency of alginate, and calcium or iron ions decrease the fouling tendency of alginate and humic acids. All obtained results can be properly explained by considering the physico-chemical properties of the investigated membranes and model foulants. [ABSTRACT FROM AUTHOR]

A concise synthetic approach to the marine natural product (+)-aureol has been achieved from readily available starting materials using obviously fewer steps in comparison to the related report in literature (6 steps versus 12 steps from (+)-sclareolide). Key steps of this protocol include a boron trifluoride-catalyzed domino 1,2-H and 1,2-methyl shifts and a nickel(II)-catalyzed cross-coupling reaction between an alkyl iodide and an aryl Grignard reagent. [ABSTRACT FROM AUTHOR]

For the first time an effective method for the preparation of 1-methoxy(dimethyl)silylmethyl- m -carborane and 1,7-bis[chloro(dimethyl)silylmethyl]- m -carborane using 1-haloidmagnesiummethyl- m -carborane and 1,7-bis[haloidmagnesiummethyl]- m -carborane was developed. It has been established that in the course of the reaction of 1-haloidmethyl- m -carboranes with magnesium both in ether and THF, simultaneously with the formation of 1-haloidmagnesiummethyl- m -carborane – the resulting Grignard reagent, proceeds the isomerization of carborane products and their remetallization with the obtained Grignard reagent. This leads to the formation of a complex mixture of products and the decrease in the yield of the resulting Grignard reagent to 43–67%. It has been shown that by using 1-haloidmethyl- m -carboranes substituted in the second carbon atom, for example, 1,7-bis[bromomethyl]- m -carborane, in the reactions for obtaining Grignard reagents, it is possible to eliminate the isomerization of carborane products and their remetallization with the target Grignard reagent 1,7-bis[bromomagnesiummethyl]-m-carborane in 90% yield. [ABSTRACT FROM AUTHOR]

An improved process for the preparation of 1-methylcyclopropanol using the Kulinkovich reaction is described. The use of titanium tetramethoxide as catalyst resulted in minimal side product formation. The reaction, isolation and purification procedures were optimized so they can be easily implemented in multi-purpose equipment. [ABSTRACT FROM AUTHOR]

A reaction of Grignard reagents with an optically pure N -sulfinylimine derived from methyl 2-formylbenzoate yields enantioenriched isoindolinones and tert -butyl sulfoxides. The products are formed by the addition of the nucleophile to N -sulfinylimine followed by cyclization to form N - tert -butylsulfinylisoindolinone, which readily undergoes substitution with a second equivalent of Grignard reagent. The reaction can be carried out in dichloromethane at room temperature or at elevated temperatures without any loss of stereoselectivity. The use of nucleophiles other than Grignard reagents has also been investigated. [ABSTRACT FROM AUTHOR]

Phenyl benzenethiosulfinate reacts with enolate anions derived from ketones to give α-phenylsulfinyl ketones directly, together with minor amounts of α-phenylsulfanyl ketones. These are easily separated by forming the water-soluble sodium salts of the sulfinyl compounds. Grignard reagents also react with phenyl benzenethiosulfinate, to give mixtures of sulfoxides and sulfides. [ABSTRACT FROM AUTHOR]

Simple synthetic approaches to pyridocarbazole and azepinocarbazole derivatives have been reported via Fischer indolization, Grignard reaction and olefin metathesis as key steps. In addition, a combination Sonogashira coupling and Pauson-Khand reaction has been used to assemble extended pyridocarbazole derivative. [ABSTRACT FROM AUTHOR]

Recently, considerable attention has been paid to the manipulation and the control of the physicochemical properties of porous silicon surfaces because of their crucial importance to the modern microelectronics industry. Hybrid structures consisting of deposited polymer on porous silicon surfaces are important to applications in microelectronics, photovoltaics and sensors (Ensafi et al., 2016; Kashyout et al., 2015; Osorio et al.; 2015; Hejjo et al., 2002) [1–4] . In many cases, the polymer can provide excellent mechanical and chemical protection of the substrate, changes the electrochemical interface characteristics of the substrate, and provides new ways to the functionalization of porous silicon surfaces for molecular recognition and sensing. In this work, porous silicon surface was modified by anodic treatment in ethynylmagnesium bromide electrolyte leading to the formation of a polymeric layer bearing some bromine substituents. Subsequently, the formed polymer is functionalized with amine molecules containing functional groups (carboxylic acid or pyridine) by a substitution reaction between bromine sites and amine groups (Hofmann reaction). The chemical composition of the modified porous silicon surfaces was investigated and the grafting of polymeric chains and functional groups on the porous silicon surface was confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) which displayed the principal characteristic peaks attributed to the different functional groups. Furthermore, the surface of the material was examined by scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

Thiochromone undergo conjugate addition reactions with arylcuprates to afford 2-substituted thioflavanones, providing an efficient synthetic approach to privileged sulfur-containing structural motifs and valuable precursor for many pharmaceuticals. Excellent yields of substituted thioflavanones are achieved with lithium diarylcuprates, lithium arylcyanocuprates and Grignard reagents with copper catalysis. This method provides a rapid entry to a variety of thioflavanones in excellent yields (up to 92%). The use of commercially available or easily prepared organometallic reagents will expedite the synthesis of a large library of thioflavanones for further synthetic applications and biological studies. [ABSTRACT FROM AUTHOR]

The ring-opening reaction of homoserine lactone with phenylmagnesium bromides was systematically examined. A reliable method to achieve β-amino acid precursors was developed by tuning the reaction conditions to favor mono-addition to the carbonyl moiety of the lactone. [ABSTRACT FROM AUTHOR]

(Hetero)arylation of [1,2,4]triazolo[1,5- a ]pyrimidine through the direct nucleophilic C H functionalization of the C-7 and C-5 positions has been implemented. The regioselective addition of a (het)aryl magnesium bromide to C-7 of 6-bromo-[1,2,4]triazolo[1,5- a ]pyrimidine, followed by eliminative aromatization of the intermediate σ H -adducts, has afforded 7-(hetero)aryl-substituted [1,2,4]triazolo[1,5- a ]pyrimidines (the S N H reaction, proceeding according to the “addition-elimination” scheme). A second treatment with a Grignard reagent has resulted in the C-5 σ H -adducts, which have been oxidized while being N -magnesium salts into [1,2,4]triazolo[1,5- a ]pyrimidines, bearing various combinations of (hetero)aromatic substituents at C-5 and C-7 (the S N H process, realizing via the “addition-oxidation” scheme). As a result of optical and electrochemical studies, the obtained compounds have proved to be promising luminescent dyes and push-pull systems. [ABSTRACT FROM AUTHOR]

Two 2-chloromagnesiothiophenes having the methoxy group at the 3- and 4-position were applied for the termination reaction of living poly(3-hexylthiophene) (P3HT). The number-averaged molecular weights of obtained P3HT approximately agreed with the theoretical value, and the high regioregularity of polymers were confirmed. The comparison of the 1 H NMR spectra of P3HT with those of model compounds in addition to the analysis of the MALDI-TOF mass spectra suggested the incorporation of the methoxythiophene unit. The termination reaction using 2-chloromagnesio-3-methoxythiophene ( GT1 ) and 2-chloromagnesio-4-methoxythiophene ( GT2 ) resulted in P3HT with the non-uniform terminal structure and that having the terminating unit at both chain ends, respectively. These facts can be ascribed to the efficiency of the elementary process (transmetallation, reductive elimination, reverse chain walking, and oxidative addition) in the catalytic cycle. On the other hand, 2-chloromagnesio-3-oxazolylthiophene ( GT3 ) exhibited the poor transmetallation activity due to the pronounced steric hindrance. It was found that the addition of LiCl for accelerating the transmetallation step and the coexistence of styrene for trapping the zero-valent nickel complex give P3HT bearing the oxazolylthiophene unit at the propagating end. [ABSTRACT FROM AUTHOR]