Phenylmagnesium Bromide Research Articles

2-Zincoethylzincation of 2-Alkynylamines and 1-Alkynylphosphines Catalyzed by Titanium(IV) Isopropoxide and Ethylmagnesium Bromide

Titanium(IV) isopropoxide and ethylmagnesium bromide catalyzed reaction of 2-alkynylamines with Et2Zn, followed by deuterolysis/hydrolysis and iodinolysis, affords substituted (Z)-pent-2-en-2,5-d 2-1-amines, (Z)-pent-2-en-1-amines (65–88%), and substituted (Z)-2,5-diiodopent-2-en-1-amines (55–63%). It is suggested that the reaction proceeds through the formation of cyclic organotitanium derivatives. The reaction between 1-alkynylphosphines and Et2Zn in the presence of catalytic amounts of Ti(O-iPr)4 and EtMgBr leads to trisubstituted 1-alkenylphosphine oxides with high regioselectivity and stereoselectivity.

Synthesis, structures, and reactivity of 9,9‐dialkoxy‐9‐silafluorenes

AbstractA series of novel 9,9‐dialkoxy‐9‐silafluorenes were synthesized, and their structures and reactivity were studied. Dehydrogenative alkoxylation of 9,9‐dihydro‐9‐silafluorene with various alcohols in the presence of PdCl2 gave the corresponding dialkoxylated products in good yields. The structures of some of the novel 9,9‐dialkoxy‐9‐silafluorenes were analyzed by X‐ray crystallography. The 9,9‐dialkoxy‐9‐silafluorenes show remarkably high reactivity toward phenylmagnesium bromide to afford substitution products.

Preparation of Phenanthridines from o-Cyanobiaryls via Addition of Organic Lithiums to Nitriles and Imino Radical Cyclization with Iodine.

Simple treatment of 2-cyanobiaryls with methyllithium, ethylmagnesium bromide, butyllithium, phenyllithium, p-methylphenyllithium, etc., followed by the reaction with water and then with molecular iodine at 60 °C provided efficiently 6-methyl-, 6-ethyl-, 6-butyl-, 6-phenyl, 6-( p-methylphenyl)phenanthridines, etc., in good yields, respectively. Here, imines formed through the addition of carbanion onto the nitriles reacted with molecular iodine to form N-iodoimines smoothly, and their warming treatment induced the formation of imino radicals that smoothly cyclized onto the aryl group to give 6-alkyl- and 6-arylphenanthridines.

Total Synthesis of Marine Alkaloid Hyellazole and its Derivatives

The total synthesis of the naturally occurring marine alkaloids hyellazole and chlorohyellazole was attempted from the corresponding easily accessible 2‐methyl‐1‐ketotetrahydrocarbazoles obtained through the Japp–Klingemann reaction, followed by Fischer indole cyclization and subsequent Grignard coupling with phenylmagnesium bromide. Grignard coupling with 2‐methyl‐1‐ketotetrahydrocarbazole unfortunately led directly to 2‐methyl‐1‐phenylcarbazole through dehydration followed by aromatization through aerial oxidation, but application of the same reaction conditions to 6‐chloro‐2‐methyl‐2,3,4,9‐tetrahydro‐1H‐carbazol‐1‐one, with careful treatment, led to the isolation of 6‐chloro‐2‐methyl‐1‐phenyl‐4,9‐dihydro‐3H‐carbazole. However, selenium dioxide oxidation of this dihydrochloro derivative led to the formation of 6‐chloro‐2‐methyl‐1‐phenyl‐9H‐carbazole. A different route was then adopted: a suitably substituted aromatic amine was used to establish the substitution pattern of the required carbazole derivative with a bromo group at C‐1, and the required phenyl group at the 1‐postion was then attached through Suzuki–Miyaura cross‐coupling to furnish hyellazole.

Microwave promoted reaction of purin-6-yl magnesium halides with aldehydes in dichloromethane at 100 °C

Treatment of a dichloromethane solution of 9-benzyl or 9-phenyl 6-iodopurine with ethereal ethylmagnesium bromide at ambient temperature gives the corresponding purin-6-yl magnesium halides. Addition of an aldehyde followed by heating at 100 °C in a microwave reactor yielded the corresponding carbinols in 52–81% yield.

Synthesis of a biofuel target through conventional organic chemistry

In this work, the biofuel target compound 2-ethyl-5,5-dimethylcyclopenta-1,3-diene (1) and its exo isomers (9a and 9b), were successfully synthesized via two different pathways from the common intermediate 4,4-dimethylcyclopent-2-ene-1-one (2). The first pathway produced the endocyclic product as a pure isomer via a triflate intermediate obtained from ketone 2 in 60% yield, followed by copper-catalyzed coupling with ethyl magnesium bromide in 63% yield. The second pathway employed a Grignard reaction with ketone 2, which generated an alcohol that was immediately subjected to mild acid-catalyzed elimination to yield primarily a mixture of exo isomers 9a and 9b in 46% yield. The preparation method developed by this work allowed for the production of a sufficient quantity of these targets to evaluate their fuel properties, which will be reported in a separate study.

Exploiting Carvone To Demonstrate Both Stereocontrol and Regiocontrol: 1,2- vs 1,4-Addition of Grignard Reagents and Organocuprates

The ability of certain organometallic reagents to react via 1,2- or 1,4-addition to an α,β-unsaturated ketone is a fundamental example of regioselectivity at the second-year undergraduate organic level. The following two experiments were designed to demonstrate this preference by exploiting carvone as an inexpensive chiral, nonracemic substrate. The first, intended for a typical undergraduate audience, makes use of phenylmagnesium bromide; the second calls for the manufacture of lithium dimethylcuprate from a stock solution of methyl lithium and copper(I) iodide and is envisioned to be carried out by upper-division students. Importantly, due to the chiral nature of carvone, these addition reactions are highly stereoselective and will provide an opportunity for students to revisit stereochemistry. Also discussed are several thoughts on assessment of student learning as well as an easy to adopt protocol that details reaction setup, aqueous workup, purification, waste management, and the analysis of products using 1H NMR spectroscopy.

A Simple Synthesis of 1,3-Diphenylpropene

A simple approach to the synthesis of 1,3-diphenylpropene isomers was developed based on Fe(acac)3-catalyzed cross-coupling of (E)- and (Z)-1,3-dichloropropenes with phenylmagnesium bromide.

An Improved Route to Purin-6-yl Magnesium Halides by Metal–Halogen Exchange in Dichloromethane

Treatment of a solution of 9-benzyl or 9-phenyl 6-iodopurine in dichloromethane with an ethereal solution of ethylmagnesium bromide at ambient temperature generates the corresponding purin-6-yl magnesium halides which react with aldehydes to give carbinols in 55–80% yield. Performing the same procedure with THF as solvent gave carbinols in much lower yields (≤15%).

Mechanistic Implications for the Ni(I)-Catalyzed Kumada Cross-Coupling Reaction

Herein we report on the cross-coupling reaction of phenylmagnesium bromide with aryl halides using the well-defined tetrahedral Ni(I) complex, [(Triphos)NiICl] (Triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane). In the presence of 0.5 mol % [(Triphos)NiICl], good to excellent yields (75–97%) of the respective coupling products within a reaction time of only 2.5 h at room temperature were achieved. Likewise, the tripodal Ni(II)complexes [(κ2-Triphos)NiIICl2] and [(κ3-Triphos)NiIICl](X) (X = ClO4, BF4) were tested as potential pre-catalysts for the Kumada cross-coupling reaction. While the Ni(II) complexes also afford the coupling products in comparable yields, mechanistic investigations by UV/Vis and electron paramagnetic resonance (EPR) spectroscopy indicate a Ni(I) intermediate as the catalytically active species in the Kumada cross-coupling reaction. Based on experimental findings and density functional theory (DFT) calculations, a plausible Ni(I)-catalyzed reaction mechanism for the Kumada cross-coupling reaction is presented.

Radiosynthesis of 1-iodo-2-[11 C]methylpropane and 2-methyl-1-[11 C]propanol and its application for alkylation reactions and C-C bond formation.

The multitude of biologically active compounds requires the availability of a broad spectrum of radiolabeled synthons for the development of positron emission tomography (PET) tracers. The aim of this study was to synthesize 1-iodo-2-[11 C]methylpropane and 2-methyl-1-[11 C]propanol and investigate the use of these reagents in further radiosynthesis reactions. 2-Methyl-1-[11 C]propanol was obtained with an average radiochemical yield of 46±6% d.c. and used with fluorobenzene as starting material. High conversion rates of 85±4% d.c. could be observed with HPLC, but large precursor amounts (32mg, 333μmol) were needed. 1-Iodo-2-[11 C]methylpropane was synthesized with a radiochemical yield of 25±7% d.c. and with a radiochemical purity of 78±7% d.c. The labelling agent 1-iodo-2-[11 C]methylpropane was coupled to thiophenol, phenol and phenylmagnesium bromide. Average radiochemical conversions of 83% d.c. for thiophenol, 40% d.c. for phenol, and 60% d.c. for phenylmagnesium bromide were obtained. In addition, [11 C]2-methyl-1-propyl phenyl sulphide was isolated with a radiochemical yield of 5±1% d.c. and a molar activity of 346±113GBq/μmol at the end of synthesis. Altogether, the syntheses of 1-iodo-2-[11 C]methylpropane and 2-methyl-1-[11 C]propanol were achieved and applied as proof of their applicability.

Reaction of (S)-homoserine lactone with Grignard reagents: synthesis of amino-keto-alcohols and β-amino acid derivatives

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.

Pyreniporphyrins: Porphyrin Analogues That Incorporate a Polycyclic Aromatic Hydrocarbon Subunit within the Macrocyclic Framework.

The first examples of porphyrin analogues incorporating pyrene units are reported. Acid-catalyzed condensation of a pyrene dialdehyde with a tripyrrane, followed by oxidation with DDQ, afforded a polycyclic aromatic hydrocarbon (PAH)-porphyrin hybrid in 38% yield. Pyreniporphyrin proved to be devoid of global aromatic character, but upon protonation aromatic mono- and dicationic species were generated. In the proton NMR spectrum for the dication, the internal CH was shifted upfield to approximately +3 ppm. NICS calculations and ACID plots confirmed the diatropic nature of these structures. Pyreniporphyrin reacted with palladium(II) acetate to give excellent yields of a palladium(II) complex that showed weakly diatropic properties. Treatment of the pyrene dialdehyde with phenylmagnesium bromide generated a dicarbinol that reacted with excess pyrrole in the presence of boron trifluoride etherate to give a tripyrrane analogue. Lewis acid catalyzed ring closure with a thiophene dialcohol in 2% ethanol-dichloromethane afforded a tetraphenylthiapyreniporphyrin in 31% yield. This porphyrinoid was nonaromatic in the free-base form but showed significant diatropicity upon protonation. These results demonstrate that PAH-porphyrin hybrids are easily accessible, and this strategy may allow the incorporation of even larger aromatic subunits.

Alternative synthesis of alverine

An efficient synthesis of alverine via iron-catalyzed double cross-coupling of (2E)-3-chloro-N-[(2E)-3-chloroprop-2-en-1-yl]-N-ethylprop-2-en-1-amine with phenylmagnesium bromide is described.

Iron(II) bipyridine complexes for the cross-coupling reaction of bromocyclohexane with phenylmagnesium bromide

Three known iron(II) complexes bearing a bipyridine ligand, [FeCl2(bpy)2] (1), [FeCl2(bpy)]2 (2) and [FeCl2(dmbpy)] (3) (bpy=2,2′-bipyridine and dmbpy=6,6′-dimethyl-2,2′-bipyridine) were employed for the cross-coupling reaction of bromocyclohexane (4) with phenylmagnesium bromide (5). These complexes catalyzed the cross-coupling reaction. Among the three catalysts, complex 2 acted as an effective catalyst to afford the cross-coupled product phenylcyclohexane (6) in 92% yield. The X-ray crystal structure analyses of 2 and 3 were demonstrated.

Synthesis and catalytic activity of nickel(II) complexes containing NCN pincer ligands

In this study, nickel(II) complexes [LmeNi(II)Cl]+(BPh4)−, [LmeNi(II)Cl]+(PF6)− and [Let2Ni(II)]+(BPh4)−2 were synthesised and characterized in the solution and solid states. Ligands Lme (C11H12N6) and Let (C13H17N6) featured a central carbene donor linked to pendant pyrazoles via either methylene or ethylene linkers. The catalytic activity of all three complexes was tested in the Kumada cross coupling reaction between phenylmagnesium bromide and aromatic halogen substituted substrates. [LmeNi(II)Cl]+(BPh4)−was found to be the most active catalyst.

Effect of 1-allyl-1-methylpyrrolidinium chloride addition to ethylmagnesium bromide electrolyte on a rechargeable magnesium battery

The ionic liquid 1-allyl-1-methylpyrrolidinium chloride was investigated as an additive to an ethylmagnesium bromide Grignard solution, for use as an advanced electrolyte in rechargeable Mg batteries. Electrochemical studies showed that the addition of the ionic liquid significantly enhanced the anodic limit of the Grignard solution by about 1V and improved the coulombic efficiency and the kinetics of Mg deposition-stripping reactions on the negative electrode. We have also demonstrated that the Grignard solution containing the ionic liquid works well as an electrolyte in a prototype cell consisting of a Mo6S8 Chevrel phase cathode and a Mg metal anode, where the original Grignard electrolyte does not function properly.

Copper-catalyzed cross-coupling reactions of non-activated primary, secondary or tertiary alkyl chlorides with phenylmagnesium bromide

Efficient copper-catalyzed cross-coupling reactions of non-activated alkyl chlorides, including primary, secondary, and tertiary alkyl chlorides, with phenyl Grignard reagents were achieved. Preparation of phenylmagnesium bromide in 2-methyltetrahydrofuran is critical for the success of the reaction. This protocol expands the synthetic toolbox for the construction of CC bonds of non-activated primary, secondary, and tertiary alkyl chlorides via copper-catalyzed cross-coupling.

Graphene Preparation by Phenylmagnesium Bromide and Its Excellent Electrical Conductivity Performance in Graphene/Poly(p-phenylene sulfide) Composites

An effective approach is reported toward the reduction of weakly exfoliated graphite oxide (WEGO) using Grignard reagent of PhMgBr as both a reducing agent and a chemical functionalizer. Graphene sheet (GS) reduction with 4 mass equiv of PhMgBr showed excellent electrical conductivity of 2.5 × 104 S/m because the π–π conjugated system among GS increased the electron transfer. The 2.5 wt % GS with 4 equiv of PhMgBr reduction was used as a filler to modify poly(p-phenylene sulfide) (PPS), and the prepared GS/PPS composites displayed higher electrical conductivity (10.5 S/m) and better mechanical properties (tensile strength 88.9 MPa and Young’s modulus 740 MPa) without much loss in the elongation at break. The reinforcing effects and high electrical conductivity could be explained by both the directional homogeneous dispersion of GS within the PPS matrix and the π–π conjugated interaction arising from the similar structural characteristics between GS and the PPS matrix.

Room temperature magnesium electrorefining by using non-aqueous electrolyte

The increasing usage of magnesium inevitably leads to a fast increase in magnesium scrap, and magnesium recycling appears extremely beneficial for cost reduction, preservation of natural resources and protection of the environment. Magnesium refining for the recovery of high purity magnesium from metal scrap alloy (AZ31B composed of magnesium, aluminum, zinc, manganese and copper) at room temperature is investigated with a non-aqueous electrolyte (tetrahydrofuran with ethyl magnesium bromide). A high purity (99.999%) of electrorefined magneisum with a smooth and dense surface is obtained after potentiostatic electrolysis with an applied voltage of 2 V. The selective dissolution of magnesium from magnesium alloy is possible by applying an adequate potential considering the tolerable impurity level in electrorefined magnesium and processing time. The purity estimation method suggested in this study can be useful in evaluating the maximum content of impurity elements.