Herein, we report an aryne triggered ring-opening fluorination protocol of a great variety of saturated sulfur heterocycles. A key factor for the success is the identification of a suitable mediator. ...Compared to previous methods, this transition-metal free protocol employs low-cost potassium fluoride as the fluorine source. The operational simplicity and mild reaction conditions allow for the rapid synthesis of a wide range of aliphatic fluoride compounds in good yields.
Boronic acids have become one of the most prevalent classes of reagents in modern organic synthesis, displaying various reactivity profiles
via
C-B bond cleavage. Herein, we describe the utilization ...of a readily available boronic acid as an efficient surrogate of hydroxide upon activation
via
fluoride complexation. The hitherto unknown aryne induced ring-opening reaction of cyclic sulfides and three-component coupling of fluoro-azaarenes are developed to exemplify the application value. Different from metal hydroxides or water, this novel hydroxy source displays mild activation conditions, great functionality tolerance and structural tunability, which shall engender a new synthetic paradigm and in a broad context offer new blueprints for organoboron chemistry. Detailed computational studies also recognize the fluoride activation mode, provide in-depth insights into the unprecedented mechanistic pathway and elucidate the reactivity difference of ArB(OH)
x
F
y
complexes, which fully support the experimental data.
Boronic acids as a tunable hydroxy source display a unique reactivity paradigm through hitherto unknown aryne-induced multicomponent reactions.
Full text
Available for:
IJS, KILJ, NUK, UL, UM, UPUK
The efficient synthesis of 2-substituted thiazoles and benzothiazoles has been accomplished employing readily available cysteine esters and 2-aminobenzenethiols as N and S sources. The reaction ...proceeds under an I2/TBHP system and involves a one-pot tandem cyclization and oxidation sequence. A diverse range of aldehydes is amenable for this transition-metal-free protocol, which provides an alternative method to rapidly access thiazole-containing molecules.
Display omitted
•Vesicle-micelle transition in a pure double-chain cationic surfactant (C6C8Br) aqueous solution.•The transition is accompanied with increase of interfacial molarities of both water ...and counterions.•The molecular configuration of C6C8Br approaches a straight line at high surfactant concentrations.•The steric effects play a vital role in reducing the interfacial packing and driving vesicle-to-micelle transition.•Significant ion-specific effects suggest that steric effects could be influenced by the interfacial composition.
Vesicles have emerged as promising drug carriers with excellent compatibility with cell membranes, holding immense potential for biomedical applications. While most reported micelle-to-vesicle transitions involve increasing surfactant or additive concentrations, the reverse vesicle-to-micelle transition remains less explored. In this study, we investigate the vesicle-to-micelle transition of hexyldimethyloctylammonium bromide (C6C8Br) using dynamic light scattering, transmission electron microscopy, and fluorescence spectroscopy. Tetradecyltrimethylammonium bromide (TTABr), a single-chain tetraalkylammonium surfactant with the same chain-length, is studied for comparison. Through the chemical trapping (CT) method, we explore the interfacial composition changes during the vesicle-to-micelle transition. Notably, C6C8Br exhibits a unique characteristic setting it apart from TTABr and other cationic surfactants. At lower concentration ranges, there is a simultaneous increase in interfacial molarities of water and bromide ions, signifying a decrease in interfacial headgroup molarity and surfactant molecule packing. Moreover, our dissipative particle dynamics (DPD) simulation results show that, as the surfactant concentration rises, the interior angle between surfactant chains widens, and the molecular configuration of C6C8Br approaches a straight line. These combined CT and DPD findings underscore the prominent role of steric effects arising from the rigidity of the double-chain. These effects become more pronounced at higher C6C8Br concentrations, leading to looser interfacial packing of surfactant monomers and driving the transition from vesicles to micelles. Interestingly, the breakage of vesicles was not observed when replacing the counterion of C6C8Br with acetate in C6C8Ac solutions. CT results suggest that the elevated interfacial acetate molarity may faciliate the compact packing of surfactant monomers and hinder vesicle-to-micelle transformation. Our study provides a molecular-level understanding of the vesicle-to-micelle transitions in C6C8Br solutions and establishes a theoretical basis for morphological control of surfactant aggregates.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A copper-catalyzed oxidative cleavage reaction of alkynes using NFSI and TBHP was described. Various terminal and internal alkyne substrates were employed to render quick access to aryl ketone ...products in moderate to good yields. NFSI not only functioned as N-centered radical precursors but also engaged in the aryl group migration. Mechanistic studies also suggested the important role of water in the title reactions.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
Silyl‐Supermacht: Die Supersilylgruppe wurde als eine bessere Schutzgruppe für Carbonsäuren untersucht. Außerdem wurden Supersilylester als stabile Carbonsäure‐Syntheseäquivalente in hoch ...stereoselektiven Aldol‐ und Mannich‐Reaktionen eingesetzt (siehe Schema). Vorteile dieser Methode sind eine einfache Photoentschützung und die schnelle Synthese von Polyketideinheiten.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The transitions between surfactant aggregate structures are triggered by changes in chemical or physical stimulations, including addition of additives. Effects of added alcohols on aggregate ...morphologies correlate strongly with alcohol chain length. The local molarities of alcohol, water, and counterions in the interfacial regions play an important role in controlling the aggregate morphologies. However, direct experimental estimates of changes of interfacial alcohol molarities during alcohol induced micelle-to-vesicle transitions have never been reported. Ellipsoidal-wormlike micelle-vesicle transitions in CTAB/KBr aqueous solutions in the presence of long-chain octanol were characterized by using combined rheological, dynamic light scattering (DLS), transmission electron microscopy (TEM) and turbidity measurements. However, the transitions are absent with added butanol. The chemical trapping method (CT) was employed to understand the differences between medium- and long-chain alcohols in determining aggregate morphology. The CT method was used to estimate interfacial water, alcohol, and counterion molarities with increasing stoichiometric alcohol concentrations. With 55 mM alcohol added, the interfacial octanol molarity is 0.9 M, which is three times higher than that for butanol. With added octanol, the ellipsoidal-wormlike micelle-vesicle transition is accompanied by a concurrent sharp increase of interfacial water molarities and a decrease of interfacial counterion molarity, which is not observed with added butanol. The CT data was also employed to estimate the changes of Israelachvili's packing parameter with increasing added alcohol concentration. Our result provides critical molecular level information for understanding the morphological transitions of CTAB/additives.
Long-chain alcohol induced micelle-to-vesicle transition is accompanied with concurrent increase of interfacial water molarity and decrease of interfacial counterion molarity.
Comprehensive Summary
A visible‐light‐enabled, photocatalyst‐free hydroacylation reaction of azodicarboxylic acid derivatives was described. This radical conjugate addition (RCA) protocol relied on ...the dual role of 4‐acyl‐1,4‐dihydropyridine (acyl‐DHP) reagents that besides being as radical reservoirs, they also enabled the conversion of radical adducts to anion intermediates via reduction. Under “catalyst‐oxidant‐additive free” conditions, a wide range of structurally different acyl hydrazide products were readily obtained in 56%—99% yields. The utility of this transformation was further demonstrated by the scale‐up synthesis and downstream derivatization.
A visible‐light‐enabled, photocatalyst‐free hydroacylation reaction of azodicarboxylic acid derivatives was described, which relied on the dual role of 4‐acyl‐1,4‐dihydropyridine (acyl‐DHP) reagents.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
An efficient and practical (hetero)benzylic sp
C-H oxidation method has been developed. Notably, this user-friendly protocol employs inexpensive potassium tert-butoxide (KO
Bu) as a promoter and ...proceeds under mild conditions using oxygen as the oxidant. A large variety of oxidation products were prepared in good to excellent yields. The utility of this "green" methodology was further demonstrated by the scale-up preparation of a biologically valued molecule.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
An efficient protocol for 2,3-sigmatropic rearrangement of allyl and propargyl thioethers is reported. The key sulfonium ylide intermediate is
in situ
formed
via S
-arylation of arynes. This ...transition metal-free method allows for ready access to a wide array of functionalized thioether derivatives in good to excellent yields.
An efficient protocol for 2,3-sigmatropic rearrangement of allyl and propargyl thioethers is reported.
