Tetrahedron Letters最新文献

The growing emphasis on environmentally friendly approaches in synthetic chemistry has gained significant attention. In this study, we utilized a waste material, Copper Slag, to catalyze the Fenton-like reaction. The catalyst’s iron content in oxide form is essential for generating radicals from ammonium persulfate, which plays a vital role in alcohol oxidation. Using Copper Slag as a catalyst offers numerous advantages, including eco-friendliness, cost-effectiveness, ease of use, and convenient workup procedures. These methods require less time and operate under mild conditions. Additionally, they leverage abundantly available and recyclable materials, which can be easily separated using magnets for efficient recovery. The results of our work demonstrate an efficient approach for oxidizing alcohols to aldehydes and ketones through the Fenton-like reaction where 20 wt% copper slag is used at room temperature using water: ethyl acetate solvent in the ratio of 1:4. Several aldehydes and ketones were successfully synthesized without any byproduct formation using this method, highlighting its effectiveness in achieving desired chemical transformations.

A simple protocol for a regioselective cross dehydrogenative reaction of 2-aryl-quinazolinones with different phenyl carboxylic acids was developed using a palladium catalyst facilitated by CH activation. Simple and readily accessible aromatic carboxylic acids were utilized as a source of benzoxylate. A one-pot method proceeded with great regioselectivity and offered mono benzoxylation product with moderate to excellent yield.

When α-alkyl substituted 1,3-dicarbonyl compounds were reacted with alkenes and alkynes in the presence of a rhenium catalyst, the reaction proceeded through the elimination of the 1,3-dicarbonyl unit to form the corresponding indanes and indenes in moderate to good yields, respectively.

2-Arylsulfonylthiophenes represent a class of important biologically active compounds. Although methods for synthesizing C2-functionalized thiophenes have been extensively reported, research on the synthesis of 2-arylsulfonylthiophenes is extremely rare. Herein, we report a method for 2-arylsulfonylthiophenes via exogenous-oxidant-free electrochemical oxidative CH sulfonylation of thiophenes, which efficiently avoid the issues of desulfonylation or over-reduction of sulfonyl groups. These reactions exhibit broad substrate scope (32 examples) and offer operationally simple, low-cost procedures in a single step.

Tetrahydrobenzofuran derivatives are widely distributed in biologically active molecules and natural products. Herein, we reported an asymmetric tandem Michael addition/interrupted Nef reaction triggered by nitromethane directly as Michael donor catalyzed by chiral 2-aminobenzimidazole bifunctional organocatalyst. A series of enantiomerically enriched trifluoromethylated hydroxyimino tetrahydrobenzofuranones were synthesized in moderate to good isolated yields (up to 97 %) and enantioselectivities (up to 80 % ee).

Cellular viscosity is a critical parameter for maintaining normal cellular functions, and its abnormalities are associated with the occurrence and development of various diseases. Therefore, real-time monitoring of cellular viscosity is of significant importance for understanding viscosity-related biological functions and revealing the pathological mechanisms of diseases. In this study, we developed a novel fluorescence probe (IP-HBO) by hybridizing dicyanisophorone with 2-(2-hydroxyphenyl)benzoxazole for monitoring of cellular microenvironment and viscosity changes in zebrafish. The probe IP-HBO combines the principles of molecular rotors and enhanced solid-state fluorescence properties, demonstrating highly specific responsiveness to viscosity, long-wavelength emission, large Stokes shift, and excellent photostability. It has been successfully employed for fluorescence imaging of viscosity in live HeLa cells and zebrafish. The construction of this probe provides a new tool for gaining insights into viscosity-related biological processes and disease mechanisms within cells.

Protein phosphorylation is a prevalent and crucial post-translational modification (PTM) of proteins. Although the use of phosphorylated amino acids as building blocks has become essential for studying phosphorylated target proteins, N-phosphorylated amino acids remain less explored because of their acid-labile NP bonds. Analogs with NP bonds replaced by CP bonds are available for pLys and pHis, retaining the α-amino acid moiety. However, a similar acid-stable pArg mimetic has not been developed. This study introduces the synthesis of an acid-stable iminoethylphosphonic acid-containing pArg mimetic with α-amino acid moiety. The α-amino acid moiety is expected to allow the developed pArg mimetic to be specifically incorporated into peptides and proteins at targeted sites with a designed amino acid sequence.

Ortoleva-King type reaction of 2-aminopyridines with easily available aromatic ketones by dual catalytic system of cobalt and iodine in chlorobenzene was proposed. The reaction made use of the in situ formation of α-halo ketones from aromatic ketones and molecular iodine. An array of functional groups were tolerated in this strategy to allow the synthesis of variously substituted imidazo[1,2-a]pyridines in moderate to good yields. Furthermore, this procedure was effectively used for the synthesis of zolimidine, a medicine that is sold as an anti-ulcer agent.

Resorcinolic macrolides are a large class of fungal natural products with conserved resorcinolic ester cores within highly variable ten- to fourteen-membered macrocycles. They exhibit a broad range of biological activities, depending largely on the size and substitution on the macrocycle bridge. Here, we report a protecting group-free synthesis of $(\pm )$-de-O-methyllasiodiplodin, a minimal resorcinolic macrolide derived from the fungus Lasiodiplodia theobromae. The route proceeds in 42% yield over 5 steps (longest linear sequence) from 9-decenoic acid, a cheap and abundant starting material. Given the broad commercial availability of a variety of similar (terminal)-enoic acids, this route provides an entry to libraries of resorcinolic macrolides with highly variable macrocycle bridges.

An efficient and sustainable approach for the microwave assisted synthesis of 2-(het)/arylquinazolin-4(3H)-ones from substituted 2-aminobenzamide and benzyl alcohols is introduced by using a reusable imidazolium based ionic liquid supported Cu(II) catalyst. This methodology exhibits high functional group tolerance and efficiently constructs desired products in good to excellent yields. Moreover, this method portrays operational simplicity, less reaction time, minimal cost and sustainable over the reported protocols. Furthermore, the catalyst can be recycled and reused up to 4 consecutive cycles with no significant loss of activity.