Search

Cyclohepta[b]indoles, prevalent in natural products and pharmaceuticals, are conventionally accessed via metal or Lewis acid‐mediated cycloadditions with prefunctionalized substrates. Our study introduces an innovative sequential catalytic assembly for synthesizing cyclohepta[b]indoles from readily available isatin derivatives. The process involves three catalytic sequences: ring‐closing metathesis, catalytic hydrogenation, and acid‐catalyzed ring expansion. The RCM of 2,2‐dialkene‐3‐oxindoles, formed by butenyl Grignard addition to 3‐allyl‐3‐hydroxy‐2‐oxindoles, yields versatile spirocyclohexene‐3‐oxindole derivatives. These derivatives undergo further transformations, including dibromination, dihydroxylation, epoxidation, Wacker oxidation at the double bond. Hydrogenation of spirocyclohexene‐3‐oxindole yields spirocyclohexane‐3‐oxindoles. Their subsequent acid‐catalyzed ring expansion/aromatization, dependent on the acid catalyst, results in either cyclohepta[b]indoles or cyclohepta[b]indole‐indoline conjugates, adding a unique synthetic dimension. The utility of this methodology is exemplified through the synthesis of an A‐FABP inhibitor, showcasing its potential in pharmaceutical applications. [ABSTRACT FROM AUTHOR]

This research introduces an eco‐friendly and innovative technique for efficiently producing p‐tolylmethanol derivatives 4(a–k) using electro‐organic synthesis based on the Grignard reaction. By employing electrochemical methods, this approach offers several advantages, including enhanced reaction efficiency and reduced environmental impact. The process involves the electrochemical generation of the Grignard reagent, followed by its reaction with appropriate substrates to yield the desired p‐tolylmethanol derivatives. Our team optimized various reaction parameters like choice of solvent, electrode material, and reaction conditions to achieve high yields and selectivity. The developed electro‐organic method demonstrated outstanding efficiency and presents a fresh and environmentally conscious approach to synthesizing p‐tolylmethanol derivatives from benzaldehyde 1(a–e) and bromobenzene 2(a–h) via the Grignard reaction, yielding excellent results (85–93%). The resulting compounds were comprehensively characterized using melting point, 1H NMR spectroscopy, and CHN analysis to verify their structures. This electro‐organic approach holds significant potential as a sustainable strategy for synthesizing valuable organic compounds. [ABSTRACT FROM AUTHOR]

(1,4-Bis (dimethylmethoxy silane) benzene was synthesized by Grignard reaction fromp-dibromobenzene, dimeth-yldimethoxy silane and magnesium chips, and then the target product 1,4-bis (dimethylhydroxy silane) benzene was prepared by hydrolysis. The product structure was characterized by infrared spectroscopy, and the effects of stirring rate, dropping time, ratio of raw materials and solvent on the yield of phenylenedisiloxane were discussed. The effects of hydrolysis catalyst and feeding time on the yield of phenylenedisiloxane hydroxyl monomer were also studied. The results showed that phenylenedisiloxy silane and phenylenedisiloxy were successfully synthesized by Grignard reaction and hydrolysis, and the optimum conditions were as follows; stirring rate 200 r/min, dropping time 3 h, the ratio of p-dibromobenzene and dimethyldimethoxy silane to magnesium 1:2. 4:2, 1400 mL tetrahydrofuran as solvent, and the yield of phenylenedisiloxy silane monomer was 64.2%. The optimum conditions for preparing phenylenedisiloxane hydroxyl monomer by hydrolysis of phenylenedisiloxane were as follows; 2500 mL H3P04 (5 wt%) phosphoric acid as hydrolysis catalyst, feed for 3.5 h, thus the yield of phenylenedisiloxane hydroxyl monomer was 77%. [ABSTRACT FROM AUTHOR]

With the strategic implementation of carbon peaking and carbon neutrality, the demand for advanced energy storage technology is rapidly increasing. Among these, the electrochemical energy storage technologies have been evolving rapidly, and have attracted intensive attention from academia and industrial sectors. In comparison with lithium-ion batteries, magnesium batteries have emerged as an important direction for developing next-generation rechargeable batteries, in view of their higher energy densities, lower cost, higher natural abundance, and environmental friendliness. For classic non-aqueous electrolytes, the formation of the passivation films with low ionic conductivities on magnesium anodes significantly hinders the electrochemical dissolution/deposition of magnesium ions, thereby greatly limiting the development of magnesium batteries. Therefore, the exploration of high-performing magnesium-ion conductive electrolyte systems is a key direction in improving the performance of magnesium batteries. In this work, from the perspective of the classical organic chemistry experiment of "Grignard reaction", we concentrate on the preparation of magnesium-ion conductive non-aqueous electrolytes and their application in magnesium battery systems. We combine the fundamentals of organic chemistry with cutting-edge technology in electrochemical energy storage, thus helping students to expand their scientific horizons, stimulating their research interests and improving their awareness of energy security and scientific literacy. [ABSTRACT FROM AUTHOR]

Sulfur monoxide (SO) is a highly reactive species that cannot be isolated in bulk. However, SO can play a pivotal role as a fundamental building block in organic synthesis. Reported herein is the design and application of a sulfinylhydrazine reagent as an easily prepared sulfur monoxide surrogate. We show facile thermal SO transfer from this reagent to dienes where a reaction using a mechanistic probe suggests the generation of singlet SO. Combined with Grignard reagents and appropriate carbon or nitrogen electrophiles, the reagent serves as an effective "SO" donor to enable the one‐pot, three‐component synthesis of sulfoxides and sulfinamides. [ABSTRACT FROM AUTHOR]

A three-stage synthetic approach made the imidazole series structurally related to clotrimazole. Firstly, benzophenone derivatives were converted to corresponding triphenylmethanol using the Grignard reaction. Then, the triphenylmethanols were reacted with thionyl chloride (SOCl2) to form triphenylchloromethanes. Finally, imidazole derivatives were obtained from substitution reactions with higher yields. All compounds and clotrimazole were characterized using spectroscopic methods, including FTIR, 1H NMR, 13C NMR, 19F NMR, and MS spectroscopies. The biological activity of the resulting compounds was tested against Candida albicans yeast and bacteria (Micrococcus luteus and Escherichia coli) using the agar diffusion test as a technique. The synthesized chemical's imidazole moiety (6b) showed significant antibacterial activity and in vitro activity against Micrococcus luteus. Molecular docking experiments were also performed to determine the modes of interactions between the produced compounds and the active site of anticandidal azole target enzyme lanosterol 14-α-demethylase (CYP51). The bioavailability of the most synthesized compounds was excellent, as evidenced by their drug-likeness and in silico ADMET characteristics. As a result, the synthesized chemicals can be thought of as potential therapeutic candidates for further research. [ABSTRACT FROM AUTHOR]

This article presents a comprehensive review of the various synthetic pathways developed over the last four decades for the synthesis of 2-acetyl-1-pyrroline (2-AP), a compound known for its significant contribution to flavor of rice. These approaches can be categorized into four main types based on retrosynthetic analysis: oxidation of suitable precursors, Grignard reactions involving 1-pyrroline carboxylates, cyclization of 6-amino 2,3-hexanedione, and hydrolysis of the enol ether of 2-AP. While these methods have aimed to provide alternative routes to produce 2-AP, some of them exhibit clear limitations, including complex and time-consuming synthetic steps, the use of expensive or hazardous chemicals. Additionally, the well-known instability of 2-AP presents significant obstacles to the development of its synthesis. Therefore, there is a pressing requirement for the creation of a simple, effective, and feasible method for preparing 2-AP. [ABSTRACT FROM AUTHOR]

Using the Grignard reaction, both heptanal and 3-phenylpropanal independently converted to 1-phenyl-3-nonanol which subsequently converted to target compound 4-methoxydecanoic acid. A short, efficient, and protective groupfree total synthesis of novel antifungal (±)-4-methoxydecanoic acid in three high-yielding steps with >75% overall yield using the oxidation of phenyl group using ruthenium trichloride to carboxy group as the key step is described. Easily available starting materials, high yield and freedom from protection and deprotection are some salient features of the synthesis. [ABSTRACT FROM AUTHOR]

Sumalactone A, a 10-membered Benzannulated macrolactone, was synthesised in a straightforward and efficient stereoselective manner using affordable and readily accessible starting materials. The main steps in this convergent synthesis are Vilsmeier-Haack formylation, Grignard reaction, alkylation of 1,3-dithiane and Yamaguchi macrolactonization.

[17] The results reported that the ligand with an isopropyl group on the oxazoline stereocentre led to an I ee i of 9% after 4 h while the ligand bearing a phenyl group at the same position led to a 16% I ee i , after 72 h. Keywords: nitriles; S N Ar alkylation; Grignard reaction; pyridine oxazoline; zinc chloride EN nitriles S N Ar alkylation Grignard reaction pyridine oxazoline zinc chloride 1834 1838 5 08/29/23 20230915 NES 230915 Graph Central to asymmetric catalysis using metal complexes is the design and development of chiral ligands with novel steric and electronic properties. [6] These sites are chosen due to the observation that alterations to the pyridine ring primarily contributes to the ligand's electronic effects while changing the substituent on the oxazoline ring mainly impacts the ligand's steric factors. Nitriles, S N Ar alkylation, Grignard reaction, pyridine oxazoline, zinc chloride. [Extracted from the article]

Here we report several useful synthetic strategies to azepino hi‐indoles, that are structural units in natural products by using commercially available indole derivatives such as 7‐bromo indole and 7‐formylindole via palladium catalyzed cross‐coupling reaction, ring closing olefin metathesis (RCM) as key steps. Later, we extended this strategy to seven‐membered fused indoles containing dioxano and dioxocano derivatives via allylation, double bond isomerization and RCM sequence as key step. Additionally, azepino indole having diene moiety was obtained by enyne metathesis and shown to be useful for Diels−Alder strategy. Along similar lines, we also report eight‐membered fused azocino indole using Grignard reaction and RCM as key steps and we demonstrated that the product obtained is useful for Fischer indolization to obtain bis‐indole derivative. Here several synthetically useful transformations were performed to generate diversity in the fused indole derivatives. All the compounds synthesized here are well characterized by NMR and HRMS data.Introduction [ABSTRACT FROM AUTHOR]

In this article, a novel synthetic route was described for the total synthesis of Sporiolide B from inexpensive and commercially available starting materials by a concise fourteen-step sequence in 6.50% overall yield. This convergent synthesis utilizes Grignard reaction, Asymmetric dihydroxylation, Yamaguchi macrolactonization and ring closing metathesis as the key steps. [ABSTRACT FROM AUTHOR]

Here, we have developed a simple synthetic approach towards synthesis of [5/6/5] and [5/5/5] fused carbocyclic frameworks from bis‐adducts of norbornadiene and cyclohexadiene derivatives with 1,2,3,4‐tetrachloro‐5,5‐dimethoxycyclopentadiene by employing atom‐economic ring‐rearrangement metathesis as a key step and these ring systems are core units in natural products. Here, we have designed highly congested polycyclic frameworks and introduced molecular complexity in a minimum number of steps. These targets contain up to seven stereo centres. Hence, this strategy can be used to design many different drug‐like molecules valuable in medicinal chemistry. [ABSTRACT FROM AUTHOR]

SP 1 sp H NMR (400 MHz, CDCl SB 3 sb ): = 7.79 (d, I J i = 6.8 Hz, 2 H), 7.50-7.44 (m, 3 H), 7.33-7.26 (m, 2 H), 7.15-7.10 (m, 2 H), 7.05-7.01 (m, 2 H), 2.36 (s, 3 H). SP 1 sp H NMR (400 MHz, CDCl SB 3 sb ): = 7.81 (d, I J i = 7.2 Hz, 2 H), 7.44 (d, I J i = 9.2 Hz, 4 H), 7.24-7.17 (m, 3 H), 7.08-7.04 (m, 2 H), 6.94 (d, I J i = 8.0 Hz, 1 H), 2.37 (s, 3 H). SP 1 sp H NMR (400 MHz, CDCl SB 3 sb ): = 7.64 (d, I J i = 7.6 Hz, 2 H), 7.38 (t, I J i = 7.6 Hz, 1 H), 7.34 (dd, I J i = 7.2, 2.4 Hz, 1 H), 7.20-7.16 (m, 3 H), 7.12-7.02 (m, 5 H), 2.37 (s, 3 H). SP 1 sp H NMR (400 MHz, CDCl SB 3 sb ): = 7.77 (d, I J i = 8.4 Hz, 2 H), 7.49 (ddd, I J i = 8.7, 5.4, 3.7 Hz, 1 H), 7.42 (d, I J i = 8.8 Hz, 3 H), 7.28-7.25 (m, 1 H), 7.21-7.19 (m, 3 H), 7.16-7.15 (m, 2 H). [Extracted from the article]

The alkaline‐earth metals Mg and Ca are too inert for the direct metalation of primary and secondary amines. Consequently, activation prior to use is required. Alternatively, the Grignard reagents RMgX (R=alkyl, aryl, X=halide) can be applied in metalation of amines. However, such a straightforward procedure for the synthesis of alkylcalcium reagents is disadvantageous due to diverse side reactions, including Wurtz‐type C−C coupling and ether degradation reactions. Therefore, suspensions of magnesium or calcium with amine can be treated in a smooth reaction with ethyl bromide in an ethereal solvent at room temperature. Intermediately formed RAeX (Ae=alkaline‐earth metal, i. e. Mg, Ca) either metalates amines yielding the corresponding amides in an in situ Grignard metalation method (iGMM) or adds across C=N bonds of imines in an in situ Grignard addition method (iGAM). The amides R'2N‐AeX (Ae=Mg: Hauser bases) undergo Schlenk‐type ligand exchange reactions yielding homoleptic Ae(NR'2)2 and potentially sparingly soluble AeX2. [ABSTRACT FROM AUTHOR]

Since its introduction in 2004, Knochel's so called Turbo‐Grignard reagents revolutionized the usage of Grignard reagents. Through the simple addition of LiCl to a magnesium alkyl an outstanding increase in reactivity can be achieved. Though the exact composition of the reactive species remained mysterious, the reactive mixture itself is readily used not only in synthesis but also found its way into more distant fields like material science. To unravel this mystery, we combined single‐crystal X‐ray diffraction with in‐solution NMR‐spectroscopy and closed our investigations with quantum chemical calculations. Using such a variety of methods, we have gained insight into and an explanation for the extraordinary reactivity of this extremely convenient reagent by determining the structure of the first bimetallic reactive species [t‐Bu2Mg ⋅ LiCl ⋅ 4 thf] with two tert‐butyl anions at the magnesium center and incorporated lithium chloride. [ABSTRACT FROM AUTHOR]

Herein, a short synthetic approach to linearly fused tricyclic enone 1 and cis‐anti‐cis type hydroxy‐triquinane 2 has been described in an efficient manner by employing tandem‐metathesis as a key step. The triquinane‐based enone 1 is prepared by a Babler–Dauben oxidation of hydroxy‐triquinane 2, which is assembled by following a three‐step sequence involving a regio‐ and stereoselective allylation, vinyl Grignard addition, and tandem‐metathesis. Our strategy relies on exo‐tricyclic ketone, which is derived from readily available exo‐dicyclopentadiene‐1‐one. The newly synthesized molecules were identified and characterized by nuclear magnetic resonance spectroscopy (NMR), and high‐resolution mass spectrometry (HRMS) data. It is worth mentioning that tricyclic enone 1 is present as a core unit of many naturally occurring polyquinanes, particularly xeromphalinone family members. Hence, our approach may be useful in the synthesis of such bioactive molecules. [ABSTRACT FROM AUTHOR]

8‐methyldecanal is a characteristic ingredient of Australian finger lime (Citrus australasica), and has found important applications in flavour and fragrance industry. A novel and practical preparation method of 8‐methyldecanal is presented. Starting from cheap and readily available 6‐chloro‐1‐hexanol, 8‐methyldecanal was prepared in five steps with an overall yield of 50.7%. [ABSTRACT FROM AUTHOR]

Magnesium and calcium are too inert to deprotonate amines directly. For the synthesis of bulky amides alternative strategies are required and in the past, N‐bound trialkylsilyl groups have been used to ease metalation reactions. The in situ Grignard reagent formation in stirred suspensions of magnesium or calcium with hydryl halide and imine in THF allows the synthesis of a plethora of amides with bulky silyl‐free substituents. Ball milling protocols partially favor competitive side reactions such as aza‐pinacol coupling reactions. Calcium is the advantageous choice for the in situ Grignard reagent formation and subsequent addition onto the imines yielding bulky calcium bis(amides) whereas the stronger reducing heavier alkaline‐earth metals strontium and barium are less selective and hence, the aza‐pinacol coupling reaction becomes competitive. Exemplary, the solid‐state molecular structures of [(Et2O)Mg(N(Ph)(CHPh2)2] and [(Et2O)2Ca(N(Ph)(CHPh2)2] have been determined. [ABSTRACT FROM AUTHOR]

Chemical reactivity plays a major role in understanding several aspects of selectivity. Therefore, in this account, we present a plethora of reactions that demonstrate our efforts in exploiting interesting cases of selectivity over the past three decades. Among them, chemoselectivity, regioselectivity and stereoselectivity are discussed. Strain, steric factors, and separation of the reacting functionalities are revealed as prominent features in generating selectivity. 1 Introduction 2 Chemoselectivity 3 Regioselectivity 4 Diastereoselectivity 5 Substrate-Based Selectivity 6 Reagent-Based Selectivity 7 Steric-Volume-Induced Selectivity 8 Role of Temperature and Reaction Time in Achieving Selectivity 9 Role of the Catalyst in Observing Selectivity 10 Separation as a Parameter for Selectivity 11 p K a (Acidity of the Active Methylene Component) 12 Sequence as a Tool for Selectivity 13 Strain of the Ring System 14 Examples of Miscellaneous Selectivity 15 Conclusions [ABSTRACT FROM AUTHOR]

A number of polycarbosilanes (PCS) with various types of terminal groups were synthesized by the Grignard reaction with (chloroalkyl)alkoxysilanes. Their structure and properties were studied by NMR, IR spectroscopy, GPC, and TGA method. The dependence of the coke residue formation on the structure of the polymer and the nature of its terminal groups has been estimated. It was demonstrated that PCS based on (chloroalkyl)trialkoxysilanes with terminal ethynyl groups are perspective precursors for SiC ceramics fabrication. [ABSTRACT FROM AUTHOR]

A macrocyclic lactone strategy for the synthesis of 5 E -isomer-free carboprost methyl ester was developed for the first time. The macrocyclic lactone being free of 5 E -isomer can be easily prepared from modified Corey lactone. The key intermediate could be used as a building scaffold to prepare carboprost methyl ester and other prostaglandins effectively. [ABSTRACT FROM AUTHOR]

Sulfoxides and sulfinamides represent versatile sulfur functional groups found in ligands, chiral auxiliaries, and bioactive molecules. Canonical two‐component syntheses, however, rely on substrates with a preinstalled C−S bond and impede efficient and modular access to these sulfur motifs. Herein is presented the application of an easily prepared, bench‐stable sulfoxide reagent for one‐pot, three‐component syntheses of sulfoxides and sulfinamides. The sulfoxide reagent donates the SO unit upon the reaction with a Grignard reagent (RMgX) as a sulfenate anion (RSO−). While subsequent trapping reactions of this key intermediate with carbon electrophiles provide sulfoxides, a range of tertiary, secondary, and primary sulfinamides can be prepared by substitution reactions with electrophilic amines. The syntheses of sulfinamide analogs of amide‐ and sulfonamide‐containing drugs illustrate the utility of the method for the rapid preparation of medicinally relevant molecules. [ABSTRACT FROM AUTHOR]

Herein, we describe new synthetic approaches to fused 5/5/6‐carbocyclic frameworks present in various polycyclic natural products such as presilphiperfolanols, lycopodium alkaloids, and cyclopiane diterpenes. Our work features, a strategically introduced hydroxy group at the tert‐carbon center of the tricyclic system which is present in presilphiperfolanols. In addition, one presilphiperfolanol analogue is reported to show the potential of strategies disclosed in this work. All the new compounds are characterized by high‐resolution NMR spectral data. The structures of critical compounds were confirmed by various chemical transformations and further supported by single‐crystal X‐ray diffraction data. Overall, our approach is simple and rely on readily available starting materials and involves a tandem‐metathesis sequence. The synthetic studies disclosed here are applicable to the synthesis of natural products and to design medicinally important targets. [ABSTRACT FROM AUTHOR]

The total synthesis of Benzannulated macrolide, (+)-Xestodecalactone A was accomplished starting from commercially available enantiomerically pure propylene oxide and 3,5-dihydroxyphenylacetic acid using Grignard reaction, alkylation of 1,3-dithiane and Yamaguchi macrolactonisation as key steps. [ABSTRACT FROM AUTHOR]

The in situ Grignard Metalation Method (iGMM) is a straightforward one‐pot procedure to quickly produce multigram amounts of Hauser bases R2N‐MgBr which are valuable and vastly used metalation reagents and novel electrolytes for magnesium batteries. During addition of bromoethane to a suspension of Mg metal and secondary amine at room temperature in an ethereal solvent, a smooth reaction yields R2N‐MgBr under evolution of ethane within a few hours. A Schlenk equilibrium is operative, interconverting the Hauser bases into their solvated homoleptic congeners Mg(NR2)2 and MgBr2 depending on the solvent. Scope and preconditions are studied, and side reactions limiting the yield have been investigated. DOSY NMR experiments and X‐ray crystal structures of characteristic examples clarify aggregation in solution and the solid state. [ABSTRACT FROM AUTHOR]

An enantioselective total synthesis of novel gingerol-related compound 4-((3S,5R)-3,5-dihydroxynonadecyl)phenol, an anti-oxidant isolated from the resinous exudates of Chilean desert plants, has been accomplished from a known commercially available 4-(but-3-enyl) phenol by a concise ten-step sequence. In this synthesis, Sharpless asymmetric dihydroxylation, Grignard reaction and Iodine-induced electrophilic cyclization have been applied as key steps. [ABSTRACT FROM AUTHOR]

An efficient synthesis of 1,1,3-trisubstituted-1H-isochromenes, 3 is reported from isochromen-1-ones, 1 and Grignard Reagents, 2a-h through sequential Grignard reactions/acid-catalyzed cyclization. The cyclization underwent smoothly with montmorillonite K10 catalyst to obtain the 1,1,3-trisubstituted-1H-isochromenes in excellent yields. [ABSTRACT FROM AUTHOR]

A new method for the preparation of halocyclobutenes is described. The developed process involves the dehydration of halocyclobutanols by using tetrafluoroboric acid–diethyl ether complex in dichloromethane at room temperature. The process allows for high yields of halocyclobutenes to be achieved by using alcohols that do not trigger the formation of isomeric allylic halides. [ABSTRACT FROM AUTHOR]

Auguste Béhal (1859-1941) was a French pharmacist that developed the chemistry of 2derivatives and studied the composition of vegetable creosotes, the decomposition of chloral, and the preparation and properties of asbolin. These studies led to the synthesis of a large number of new organic compounds, several of them with therapeutic value. [ABSTRACT FROM AUTHOR]

Trialkyl and triaryl phosphines are important classes of ligands in the field of catalysis and materials research. The wide usability of these low-valent phosphines has led to the design and development of new synthesis routes for a variety of phosphines. In the present work, we report the synthesis and characterization of some mixed arylalkyl tertiary phosphines via the Grignard approach. A new asymmetric phosphine is characterized extensively by multi-spectroscopic techniques. IR and UV–Vis spectra of some selected compounds are also compared and discussed. Density functional theory (DFT)-calculated results support the formation of the new compounds. [ABSTRACT FROM AUTHOR]

The stereoselective total synthesis of (+)-casuarine has been achieved via a functionalized pyrrolidine obtained from a chiral 1,3-oxazine. The synthetic strategy includes a stereoselective dihydroxylation reaction using osmium tetroxide and stereoselective Grignard-type vinyl addition reaction as the key steps to generate the two new stereocenters. The dihydroxylation catalyzed by osmium tetroxide formed anti -amino alcohol, and the vinyl addition formed syn -alcohol. (+)-Casuarine was prepared from the functionalized pyrrolidine over 11 steps in an overall yield of 16%. [ABSTRACT FROM AUTHOR]

A one‐pot, three‐step protocol for the preparation of Grignard reagents from organobromides in a ball mill and their subsequent reactions with gaseous carbon dioxide (CO2) or sodium methyl carbonate providing aryl and alkyl carboxylic acids in up to 82 % yield is reported. Noteworthy are the short reaction times and the significantly reduced solvent amounts [2.0 equiv. for liquid assisted grinding (LAG) conditions]. Unexpectedly, aryl bromides with methoxy substituents lead to symmetric ketones as major products. [ABSTRACT FROM AUTHOR]

The generation of positionally stable purin‐2‐ and 6‐yl magnesium halides is complicated by the often very rapid isomerization to give the 8‐yl Grignards. By conducting the reaction in dichloromethane (DCM), we demonstrated that the anion isomerization can be stopped and these stable purin‐2‐ and 6‐yl Grignards react directly with a broad scope of aldehydes in good yields. Furthermore, purine functionalization with ketones has been achieved for the first time in the presence of LaCl3 ⋅ 2LiCl. Density functional theory calculations offer a possible explanation of the special role played by solvent in this chemistry and show that in DCM the C−Mg bond has a less polar character, whereas in THF it is predominantly ionic and much more basic in nature. [ABSTRACT FROM AUTHOR]

The synthesis of ketones through addition of organometallic reagents to aliphatic carboxylic acids is a straightforward strategy that is limited to organolithium reagents. More desirable Grignard reagents can be activated and controlled with a bulky aniline‐derived turbo‐Hauser base. This operationally simple procedure allows the straightforward preparation of a variety of aliphatic and perfluoroalkyl ketones alike from functionalized alkyl, aryl and heteroaryl Grignard reagents. [ABSTRACT FROM AUTHOR]

Methods involving C–C bond formation are continuously being innovated due to their importance in the creation and modification of important organic molecules. The classic Grignard reaction demonstrates C–C bond formation with reagents that are usually accessible in undergraduate laboratory classes. Oftentimes, to make the Grignard reaction viable, the reactions are assisted by heating at elevated temperatures or with the use of a catalyst accompanied by solvents that have been dried using highly reactive sodium metal (Na0)─conditions which increase the risk of a laboratory fire or explosion. For this work, a method to conduct Grignard reactions under mild conditions utilizing sand-paper-polished Mg ribbons and solvent dried using molecular sieves was developed. The conscientious, accessible, and easy-to-follow preparation of both the solvent and the Mg ribbons is found to contribute more to the percent conversion of reagents to products. The average percent conversion with the proposed method ranged from 76.8% to 99.5% based on 1H NMR results. This makes the Grignard demonstration possible even for the most humid, tropical locations. [ABSTRACT FROM AUTHOR]

A concise total synthesis of (-)-Curvularin have been synthesized from commercially available (S)-(−)-propylene epoxide and (3,5-Dimethoxyphenyl)acetic acid. The key steps involved in the synthesis are Vilsmeier-Haack formylation, Grignard reaction, alkylation of 1,3-dithiane and Yamaguchi macrolactonization. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Xinyang Normal University Natural Science Edition is the property of Journal of Xinyang Normal University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The large originator pharmaceutical companies need more and more new compounds for their molecule banks, because high throughput screening (HTS) is still a widely used method to find new hits in the course of the lead discovery. In the design and synthesis of a new compound library, important points are in focus nowadays: Lipinski’s rule of five (RO5); the high Fsp3 character; the use of bioisosteric heterocycles instead of aromatic rings. With said aim in mind, we have synthesized a small compound library of new spiro[cycloalkane-pyridazinones] with 36 members. The compounds with this new scaffold may be useful in various drug discovery projects.

A wide range of polyfunctionalized di(hetero)aryl- and dialkenyl-magnesium reagents are prepared in toluene within 10 to 120 minutes between –78 °C and 25 °C via an I/Mg- or Br/Mg-exchange reaction using reagents of the general formula R2 Mg (R = s Bu, Mes). Highly sensitive functional groups, such as triazene or nitro, are tolerated in these exchange reactions, enabling the synthesis of various functionalized (hetero)arene and alkene derivatives after quenching with several electrophiles including allyl bromides, acyl chlorides, aldehydes, ketones, and aryl iodides. [ABSTRACT FROM AUTHOR]

A big problem with the chemistry literature is that it is not standardized with respect to precise operational parameters, and real time corrections are hard to make without expert knowledge. This lack of context means difficult reproducibility because many steps are ambiguous, and hence depend on tacit knowledge. Here we present the integration of online NMR into an automated chemical synthesis machine (CSM aka. "Chemputer" which is capable of small‐molecule synthesis using a universal programming language) to allow automated analysis and adjustment of reactions on the fly. The system was validated and benchmarked by using Grignard reactions which were chosen due to their importance in synthesis. The system was monitored in real time using online‐NMR, and spectra were measured continuously during the reactions. This shows that the synthesis being done in the Chemputer can be dynamically controlled in response to feedback optimizing the reaction conditions according to the user requirements. [ABSTRACT FROM AUTHOR]

The stereoselective synthesis of substituted morpholine derivatives has been achieved through a two-step process involving diastereoselective addition of a Grignard reagent to a sulfinyl imine, followed by cyclization. [ABSTRACT FROM AUTHOR]

Trialkyl and triaryl phosphines are important classes of ligands in the field of catalysis and materials research. The wide usability of these low-valent phosphines has led to the design and development of new synthesis routes for a variety of phosphines. In the present work, we report the synthesis and characterization of some mixed arylalkyl tertiary phosphines via the Grignard approach. A new asymmetric phosphine is characterized extensively by multi-spectroscopic techniques. IR and UV–Vis spectra of some selected compounds are also compared and discussed. Density functional theory (DFT)-calculated results support the formation of the new compounds.

The new semisynthetic oripavine derivative 3‐O‐trityl‐6‐O‐desmethyl‐dihydroetorphine was synthesized from the poppy alkaloid thebaine in a six‐step procedure. This compound can be applied as precursor for the radiosynthesis of [6‐O‐methyl‐11C]‐dihydroetorphine ([11C]DHE). We present a detailed description of 1H and 13C NMR data of reference standards and precursors for [6‐O‐methyl‐11C]‐ and [6‐O‐(2‐[18F]fluoroethyl]orvinols. This includes the complete assignment for 19 oripavine derivatives examined in 1D and 2D NMR experiments. We also investigated the molecular basis for regioselectivity of fluoroalkylation of 3‐O‐trityl‐6‐O‐desmethyl‐phenethyl‐orvinol (TDPEO) using computational methods. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Science & Engineering (1673-2812) is the property of Journal of Materials Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The regioselectivity (r.s.) and enantiospecificity (e.s.) of the substitution reactions of secondary propargylic alcohol derivatives using reagents derived from ArMgBr and Cu salts were studied. First, the picolinate, 3‐methylpicolinate, and diethylphosphonate derivatives of Ph(CH2)2CH(OH)C≡CTMS were reacted with PhMgBr/CuCN in ratios of 2.5:2.7–2.5:0.25. The use of 2.5:0.25 ratio in THF/DME (6:1) at 0 °C for 1 h afforded the α‐substitution product from the phosphate with ≥98 % r.s. and 99 % e.s. CuBr⋅Me2S gave similar selectivity. The reaction system was then applied to phosphates derived from R1CH(OH)C≡CR2 and ArMgBr to obtain synthetically sufficient r.s. and e.s. values with R2=TMS, Ph, whereas iPr was borderline in terms of size as an R1 substituent. The presence of a substituent at the o‐position of Ar marginally affected the selectivity. We also found that the use of PhMgBr/Cu(acac)2 in a 2:1 ratio in THF produced the γ‐substitution products (allenes) with high r.s. and e.s. [ABSTRACT FROM AUTHOR]

An investigation of the reaction of 3,4- trans -isoxazolidine-4,5-diols with Grignard reagents is described for the first time. Their resemblance to five-membered cyclic hemiacetals allows them to react as α-hydroxy-β-(hydroxyamino)aldehydes in a highly stereoselective manner, providing anti , syn -γ-(hydroxyamino)-α,β-diols in moderate yields and with good to excellent syn -diastereoselectivities, which can be improved by the addition of anhydrous cerium chloride. The obtained (hydroxyamino-)diols serve as suitable precursors of anti , syn -γ-amino-α,β-diols that represent valuable scaffolds for the synthesis of various biologically active compounds. [ABSTRACT FROM AUTHOR]

The dynamic equilibria of organomagnesium reagents are known to be very complex, and the relative reactivity of their components is poorly understood. Herein, a combination of DFT calculations and kinetic experiments is employed to investigate the detailed reaction mechanism of the Pummerer coupling between sulfoxides and turbo‐organomagnesium amides. Among the various aggregates studied, unprecedented heterometallic open cubane structures are demonstrated to yield favorable barriers through a concerted anion‐anion coupling/ S−O cleavage step. Beyond a structural curiosity, these results introduce open cubane organometallics as key reactive intermediates in turbo‐organomagnesium amide mixtures. [ABSTRACT FROM AUTHOR]