focalinterest.net

Tag: Organic Chemistry & Synthesis

  • Photoredox method enables deoxytrifluoromethoxylation of phenols

    What the study found

    The study reports a photoredox strategy for deoxytrifluoromethoxylation of phenols, meaning the replacement of an oxygen-linked group in phenols with a trifluoromethoxy group. The authors say the method works under mild conditions, applies to a range of phenolic substrates, and shows excellent selectivity among multiple carbon-oxygen bonds.

    Why the authors say this matters

    The authors conclude that using organic photoredox catalysts allows the reaction to proceed under mild conditions. The study suggests this approach is broadly applicable to phenolic substrates and can distinguish among multiple carbon-oxygen bonds with high selectivity.

    What the researchers tested

    The researchers developed a photoredox approach using organic photoredox catalysts. They used the tendency of the OCF3 anion to decompose into difluorophosgene, which then reacts in situ with phenol to form an aryl carbonofluoridate and lower the bond energy of the Csp2-O bond.

    What worked and what didn't

    According to the abstract, the strategy successfully enabled deoxytrifluoromethoxylation of phenols. It was described as mild, broadly applicable to various phenolic substrates, and highly selective among multiple C-O bonds. The abstract does not describe any failed substrates, side reactions, or comparative limitations.

    What to keep in mind

    The available summary does not provide details on yields, substrate scope limits, reaction times, or specific examples. Limitations are not described in the abstract.

    • The article reports a photoredox strategy for deoxytrifluoromethoxylation of phenols.
    • Organic photoredox catalysts were used to run the method under mild conditions.
    • The approach is described as broadly applicable to various phenolic substrates.
    • The authors say the method shows excellent selectivity among multiple C-O bonds.
    • The abstract does not describe specific limitations or failed cases.

  • Asymmetric Michael addition produced N–N atropisomers with multiple stereocenters

    What the study found

    The study reports that indole-derived maleimides can be desymmetrized to form N-N atropisomers, which are molecules with restricted rotation around an N-N bond that creates axial chirality. The reaction also established remote vicinal quaternary-tertiary stereocenters.

    Why the authors say this matters

    The authors note that N-N atropisomers are of interest because of their distinctive stereochemical properties and their presence in biologically active molecules and chiral catalysts. The findings suggest a way to build these structures with multiple stereocenters in one reaction.

    What the researchers tested

    The researchers tested a desymmetrization approach using asymmetric Michael addition on indole-derived maleimides. They evaluated whether the reaction could simultaneously create N-N axial chirality and remote vicinal quaternary-tertiary stereocenters.

    What worked and what didn't

    The reaction gave the corresponding products in excellent yield and with high stereocontrol. The abstract reports yields up to 99%, enantiomeric excess up to 99% ee, and diastereomeric ratios greater than 20:1, and it does not describe any specific cases that failed.

    What to keep in mind

    The available summary does not describe substrate scope, reaction conditions, or limitations. It also does not report detailed mechanistic evidence or any unsuccessful examples.

    • The study reports a route to N-N atropisomers from indole-derived maleimides.
    • The reaction was an asymmetric Michael addition used for desymmetrization.
    • It formed both N-N axial chirality and remote vicinal quaternary-tertiary stereocenters in one step.
    • The abstract reports up to 99% yield, up to 99% ee, and greater than 20:1 dr.
    • The abstract says N-N atropisomers are of interest in biologically active molecules and chiral catalysts.

  • Hydrofluorocarbons can be recycled into useful fluorides

    What the study found

    The study found that hydrofluorocarbons can be defluorinated with a potassium base to produce anhydrous potassium fluoride, which can then be used to make many fluorinated products through a one-pot transfer fluorination process. The products named in the abstract include sulfonyl fluorides, aryl fluorides, alkyl fluorides, and several p-block fluorides.

    Why the authors say this matters

    The authors say this matters because fluorochemicals are widely used, but there is increasing concern about how they are produced and their negative effects on health and the environment. The study suggests that recycling fluorochemicals by transfer fluorination could provide a route to reuse fluorine-containing materials.

    What the researchers tested

    The researchers treated hydrofluorocarbons with potassium bases, specifically KHMDS or KOtBu, to trigger rapid defluorination. They then used the resulting potassium fluoride in a one-pot transfer fluorination process and examined the mechanism with density functional theory calculations. They also reported scale-up approaches using batch chemistry and flow chemistry.

    What worked and what didn't

    The abstract reports that rapid defluorination produced anhydrous potassium fluoride, and that this fluoride could be used to prepare a wide range of fluorinated organic and inorganic molecules. The recycling scope included industrial refrigerants, hydrofluoroolefins, fluoroethers, perfluorooctanoic acid, and poly(vinylidene) difluoride. The abstract does not describe failures or products that could not be made.

    What to keep in mind

    The available summary does not provide detailed yield data, selectivity information, or specific limitations of the method. It also does not describe which substrates were less successful, beyond listing the classes included in the scope.

    • Hydrofluorocarbons were converted by potassium bases into anhydrous potassium fluoride.
    • The resulting fluoride was used in a one-pot transfer fluorination process.
    • The method produced sulfonyl fluorides, aryl fluorides, alkyl fluorides, and p-block fluorides.
    • The scope included refrigerants, hydrofluoroolefins, fluoroethers, perfluorooctanoic acid, and poly(vinylidene) difluoride.
    • The authors also investigated the mechanism with density functional theory calculations and reported batch and flow scale-up.

  • Indoles were converted into α-perfluoroalkylamino derivatives

    What the study found

    The study reports a new way to make α-perfluoroalkylamino indole derivatives, which are indole molecules carrying nitrogen-substituted perfluoroalkyl groups. The transformation works under mild conditions, tolerates a range of functional groups, and gives yields up to 80%.

    Why the authors say this matters

    The authors conclude that this is a practical strategy for defluorinative functionalization, meaning the selective modification of fluorine-containing groups by removing fluorine during the reaction. They say it opens new avenues for making structurally diverse heteroarenes, which are ring-shaped molecules containing atoms such as nitrogen.

    What the researchers tested

    The researchers examined a sequential perfluoroalkylation and defluoroamination of indoles. They also carried out mechanistic investigations, including a proposed cascade process involving sulfinate-derived perfluoroalkyl radicals, hexamethyldisilazane (HMDS), C-F bond cleavage, and C-N bond formation.

    What worked and what didn't

    The reaction succeeded in producing a series of α-perfluoroalkylamino indole derivatives. It proceeded under mild conditions with good functional group tolerance, and the reported yields reached up to 80%. The abstract does not describe specific failures or unsuccessful substrates.

    What to keep in mind

    The available summary does not provide detailed limitations, such as substrate-specific exceptions, side reactions, or scale-up data. The mechanistic picture is described as supported by investigations, but the abstract does not give further experimental detail.

    • A new sequential perfluoroalkylation and defluoroamination method for indoles was reported.
    • The reaction gave α-perfluoroalkylamino indole derivatives in yields up to 80%.
    • The method was described as mild and tolerant of many functional groups.
    • Mechanistic studies supported a cascade involving sulfinate-derived perfluoroalkyl radicals and HMDS-mediated C-F bond cleavage.

  • Metal-free trifluoromethylalkynylation of unsaturated peptides

    What the study found

    The study reports the first metal-free trifluoromethylalkynylation of unsaturated amino acids and peptides. In plain terms, it adds both a trifluoromethyl group and an alkyne group to peptide-based molecules in one step.

    Why the authors say this matters

    The authors say that simultaneous incorporation of alkyne and trifluoromethyl groups enables rapid access to multifunctional peptide structures. The study suggests this provides a practical and versatile route to valuable scaffolds, which are molecular frameworks used in chemical synthesis.

    What the researchers tested

    The researchers tested a metal-free trifluoromethylation method on unsaturated amino acids and peptides. They used a cheap trifluoromethylation reagent under mild conditions.

    What worked and what didn't

    The abstract states that the method worked for unsaturated amino acids and peptides and enabled concurrent incorporation of trifluoromethyl and alkynyl groups. It also describes the approach as the first of its kind, but it does not report specific yields, failures, or side reactions.

    What to keep in mind

    The available summary does not describe detailed experimental scope, performance data, or limitations. It also does not state how broadly the method applies beyond the unsaturated amino acids and peptides mentioned.

    • The study reports the first metal-free trifluoromethylalkynylation of unsaturated amino acids and peptides.
    • The method adds both a trifluoromethyl group and an alkyne group in one step.
    • The authors used a cheap trifluoromethylation reagent under mild conditions.
    • The abstract says the approach offers a practical and versatile route to valuable scaffolds.
    • No detailed results, yields, or limitations are given in the provided abstract.

  • Photocatalysis enabled synthesis of alpha-trifluoromethyl amidines and imidates

    What the study found

    The study reports a mild, metal-free photocatalytic method for making alpha-trifluoromethyl amidines and imidates, which are molecular scaffolds used in bioactive compounds and functional materials. The approach uses readily accessible starting materials and is described as having perfect atom economy, meaning all atoms from the reactants are incorporated into the products.

    Why the authors say this matters

    The authors state that general methods for synthesizing these compounds remain underdeveloped, so their study suggests a useful way to access these structures more directly. They also note that the products are valuable because amidine and imidate motifs are common in bioactive compounds and functional materials, and the CF3 group can improve physicochemical and pharmacological properties.

    What the researchers tested

    The researchers tested a photocatalytic protocol that generates 3-(trifluoromethyl)ketenimines in situ from trifluoroacylsilanes and isocyanides. These intermediates were then trapped with anilines and phenols to form the target amidines and imidates. Mechanistic investigations included density functional theory (DFT) calculations, a computational method used to study reaction pathways.

    What worked and what didn't

    The method was reported to have broad substrate scope, high efficiency, and generally good yields. The abstract does not describe specific substrates that failed or conditions that did not work. It also states that the reaction proceeds preferentially via a triplet carbene intermediate, and a plausible mechanism for the key coupling step is proposed.

    What to keep in mind

    The abstract does not provide detailed limitations, such as exact scope boundaries, failed examples, or comparative performance against other methods. The mechanistic explanation is presented as supported by calculations and as a plausible proposal, rather than as direct experimental proof.

    • A mild, metal-free photocatalytic strategy was reported for alpha-trifluoromethyl amidines and imidates.
    • The method uses trifluoroacylsilanes and isocyanides to generate 3-(trifluoromethyl)ketenimines in situ.
    • Anilines and phenols are used as nucleophiles to trap the intermediates and form the products.
    • The abstract says the protocol has broad substrate scope, high efficiency, and generally good yields.
    • DFT calculations support a preferential pathway through a triplet carbene intermediate.