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Tag: Inorganic & Coordination Chemistry

  • Tetraalkynylmagnesium complexes enabled propargylamine synthesis

    What the study found

    The study found that alkynylation of N-aryl imines, an underexplored reaction, proceeds efficiently with tetraalkynyl magnesium ate complexes and BF3·OEt2. This gives propargylamines, and the resulting products can be further converted into N-heterocycles, which are ring-shaped compounds containing nitrogen.

    Why the authors say this matters

    The authors present this as a strategy for propargyl amine synthesis. The findings suggest a useful way to access propargylamines and then convert them into N-heterocycles.

    What the researchers tested

    The researchers tested the alkynylation of N-aryl imines using tetraalkynyl magnesium ate complexes in the presence of BF3·OEt2. The abstract does not describe additional experimental details.

    What worked and what didn't

    The reaction worked efficiently and afforded the corresponding propargylamines in good yields. The abstract does not report failed substrates, side reactions, or comparison conditions.

    What to keep in mind

    The available summary gives only a brief description of the reaction and its outcome. It does not provide detailed scope, limitations, or experimental conditions beyond the use of tetraalkynyl magnesium ate complexes and BF3·OEt2.

    • Alkynylation of N-aryl imines was reported as an underexplored reaction.
    • Tetraalkynyl magnesium ate complexes and BF3·OEt2 enabled the reaction efficiently.
    • The reaction produced propargylamines in good yields.
    • The resulting propargylamine products could be converted into N-heterocycles.
    • The abstract does not describe detailed limitations or scope.

  • Barium promoted alkylation of isatin derivatives was achieved

    What the study found

    The study found that Barbier-type alkylation of isatin derivatives could be achieved using metallic barium as the promoter. The reaction was reported to work with selected alkyl iodides and benzylic or prenylic bromides.

    Why the authors say this matters

    The authors do not state a broader application or significance beyond showing that metallic barium can promote this type of alkylation. The findings indicate a new promoter for this reaction class.

    What the researchers tested

    The researchers tested Barbier-type alkylation of isatin derivatives with alkyl halides under metallic barium-promoted conditions. The abstract says the halides included alkyl iodides and benzylic bromides, as well as prenylic bromides.

    What worked and what didn't

    The reaction worked with selected alkyl iodides and with benzylic and prenylic bromides under metallic barium-promoted Barbier-type conditions. The abstract does not describe failures, yields, or cases where the method did not work.

    What to keep in mind

    The abstract describes the reaction as applicable only to selected substrates, so the scope appears limited. No further limitations, performance details, or mechanistic explanation are provided in the available summary.

    • Metallic barium was used to promote Barbier-type alkylation of isatin derivatives.
    • The reaction was reported for selected alkyl iodides.
    • Benzylic bromides and prenylic bromides were also included in the reported scope.
    • The abstract does not give yields, side reactions, or failed examples.

  • Thiolate-mediated cyclization yields 2-quinolones from 2-aminocinnamic acids

    What the study found

    The study reports a new way to make 2-quinolones, a class of nitrogen-containing ring compounds, from (E)-2-aminocinnamic acid derivatives using a thiolate as a nucleophilic promoter. The authors also report that the method works for all regioisomers of 2-aza-quinolones from 2-amino-aza-cinnamate derivatives.

    Why the authors say this matters

    The authors say the simple operation, easy isolation of quinolones by recrystallization, and gram-scale scalability highlight the practical utility of the protocol. The study suggests the method may be useful as a practical synthesis route for quinolone and aza-quinolone derivatives.

    What the researchers tested

    The researchers tested a cyclization protocol in which a thiolate first adds to (E)-2-aminocinnamic acid derivatives, forming β-sulfide-substituted dihydrocinnamic acid intermediates. They then examined whether these intermediates could undergo intramolecular condensation between amino and carboxyl groups, followed by elimination of hydrogen sulfide, to form the target ring system.

    What worked and what didn't

    A broad range of 2-aminocinnamic acid derivatives was compatible with the transformation, and the corresponding 2-quinolone derivatives were obtained in excellent yields. The abstract does not describe substrate classes that failed or specific cases that performed poorly.

    What to keep in mind

    The available summary does not provide detailed reaction conditions, specific yield values, or a list of incompatible substrates. It also does not describe experimental limitations beyond the stated scope of the reported derivatives and the mention of gram-scale scalability.

    • A thiolate-mediated protocol was developed for making 2-quinolones from (E)-2-aminocinnamic acid derivatives.
    • The proposed sequence involves thiolate addition, intramolecular condensation, and hydrogen sulfide elimination.
    • The method also applies to 2-amino-aza-cinnamate derivatives, giving all regioisomers of 2-aza-quinolones.
    • The abstract reports broad substrate compatibility and excellent yields.
    • The authors note simple operation, recrystallization-based isolation, and gram-scale scalability.

  • Organocatalytic esterification produced phosphinate esters from P(O)-OH compounds

    What the study found

    The study reports a metal-free organocatalytic method for directly esterifying P(O)-OH compounds with alcohols to make phosphinate esters. The authors describe it as sustainable and scalable, with moderate to excellent yields for 39 organophosphinates.

    Why the authors say this matters

    The authors say the method provides a sustainable and scalable route to phosphinate esters. The study suggests this is environmentally benign because it avoids strong oxidants, halides, and bases.

    What the researchers tested

    The researchers introduced a catalytic variant of the Mitsunobu reaction to organophosphorus chemistry, using a carbonyl group-containing P=O catalyst and Dean-Stark water removal. They tested direct esterification of P(O)-OH compounds with alcohols and examined the mechanism with DFT calculations (density functional theory, a computational chemistry method).

    What worked and what didn't

    The protocol showed remarkable functional group tolerance and produced 39 organophosphinates in moderate to excellent yield. The abstract does not describe specific substrates that failed or cases with low performance.

    What to keep in mind

    The available summary does not give detailed substrate-by-substrate limitations or examples of unsuccessful reactions. It also does not provide experimental conditions, reaction times, or comparative performance against other methods beyond the stated absence of strong oxidants, halides, or bases.

    • A metal-free organocatalytic route was reported for direct esterification of P(O)-OH compounds with alcohols.
    • The method was described as a sustainable and scalable way to make phosphinate esters.
    • The authors report 39 organophosphinates were synthesized in moderate to excellent yield.
    • The protocol is said to avoid strong oxidants, halides, and bases.
    • DFT calculations supported a mechanism involving dehydration, ligand exchange, proton transfer, and ring-opening.

  • 2-Lithiomethylindoles enable broad 2-functionalized indole synthesis

    What the study found

    The study found that 2-lithiomethylindoles, which are organolithium reagents, can be used as versatile starting points for making many 2-functionalized indoles. The authors report that the approach worked with several kinds of electrophiles and with multiple indole substrates.

    Why the authors say this matters

    The authors suggest the method is valuable because it opens access to new functionalized indole derivatives, a useful class of compounds in synthesis. They also say that using deep eutectic solvents, mixtures that can support reactions under air- and moisture-tolerant conditions, highlights a greener and operationally simple character.

    What the researchers tested

    The researchers tested a protocol for generating 2-lithiomethylindoles, using BuLi (n-butyllithium) at room temperature as the most effective condition. They then trapped the organolithium reagents with electrophiles such as Weinreb amides, ketones, alkyl bromides, and epoxides, and applied the method to different 2-methylindoles and 2-benzylindoles.

    What worked and what didn't

    BuLi at room temperature was reported as the most effective way to form the 2-lithiomethylindole intermediates. The intermediates were efficiently trapped with diverse electrophiles, giving a broad range of C2-functionalized indoles in good yields, and the method was also successful across indoles with different substituents on the benzenoid ring, at C3, and on nitrogen.

    What to keep in mind

    The abstract does not describe specific failed substrates, low-yield cases, or detailed limitations. It also provides only a brief summary of the subsequent derivatization example, which is the two-step preparation of 2,4-disubstituted carbazoles.

    • 2-lithiomethylindoles were used as intermediates for making 2-functionalized indoles.
    • BuLi at room temperature was described as the most effective protocol for forming the organolithium reagents.
    • Weinreb amides, ketones, alkyl bromides, and epoxides were all used as trapping agents.
    • The method worked with differently substituted 2-methylindoles and with 2-benzylindoles.
    • Deep eutectic solvents allowed the reactions to proceed under air- and moisture-tolerant conditions.

  • P–H bond pKa values were measured for triorganophosphonium bistriflimides in toluene

    What the study found

    The study reports experimentally determined pKa values, meaning acidity values, for P–H bonds in triorganophosphonium bistriflimides in toluene. The measured values showed good linear correlation with values from DFT, or density functional theory, calculations.

    Why the authors say this matters

    The authors conclude that these pKa values in toluene are expected to provide guidelines for the rational design of catalytic reactions. They also note that triorganophosphonium salts are important reagents in transition metal-catalyzed organic synthesis.

    What the researchers tested

    The researchers experimentally determined pKa values for P–H bonds in 8 triorganophosphonium bistriflimides and 13 tool compounds in toluene. They used the self-dissociation equilibrium constant of an anchor compound and combined UV-visible and 31P{1H} NMR spectroscopy.

    What worked and what didn't

    The approach yielded pKa values for the triorganophosphonium compounds and the comparison compounds in toluene. The experimentally determined values exhibited good linear correlations with the corresponding DFT-calculated values.

    What to keep in mind

    The abstract does not describe experimental limitations or failures. The reported pKa values are specific to toluene and to the compounds studied here.

    • Experimentally determined pKa values were reported for P–H bonds in triorganophosphonium bistriflimides in toluene.
    • The study included 8 triorganophosphonium bistriflimides and 13 tool compounds.
    • UV-visible and 31P{1H} NMR spectroscopy were used along with an anchor compound equilibrium constant.
    • The measured pKa values showed good linear correlation with DFT-computed values.
    • The authors say the values may guide rational design of catalytic reactions.