Construction of the 2-Amino-1,3-selenazole Skeleton via PhICl2/KSeCN-Mediated Selenocyanation/Cyclization

Construction of 5-Amino-1,2-Selenazole Scaffolds through N-Selenocyanation/Cyclization of Enaminones Using KSeCN

A metal-free and mild approach for constructing 5-amino-1,2-selenazole skeletons by NBS/KSeCN-mediated N-selenocyanation and nucleophilic cyclization of β-enaminones has been developed. Various isoselenazole compounds and the isoselenazolyl derivatives of anti-inflammatory medicines, including isosepac, oxaprozin, and ibuprofen, have been obtained with good yields. This efficient, "one-pot", and atomic economy strategy may represent an alternative route for the construction of a 1,2-selenazole framework via the "+SeCN" pathway and provide new access to heterocycles containing a Se-N bond.

Glutathione Peroxidase-like Antioxidant Activity of 1,3-Benzoselenazoles: Synthesis and In Silico Molecular Docking Studies as Pancreatic Lipase Inhibitors

The synthesis of 1,3-benzoselenazoles was achieved by the reaction of corresponding bis[3-amino-N-(p-tolyl)benzamide-2-yl] diselenide, bis[3-amino-N-(4-methoxyphenyl)benzamide-2-yl] diselenide, and bis[3-amino-N-(4-(dimethylamino)phenyl) benzamide-2-yl] diselenide with aryl aldehydes. The 1,3-benzoselenazoles continued to exist as planar molecules due to the presence of secondary Se···O interactions as revealed by the single-crystal X-ray analysis. The presence of secondary Se···O interactions in 1,3-benzoselenazoles was confirmed using natural bond orbital (NBO) and atoms in molecules (AIM) calculations. Nucleus-independent chemical shift (NICS) values suggested the presence of aromatic character in a five-membered benzoselenazole heterocyclic ring. The glutathione peroxidase (GPx)-like antioxidant activity of all 1,3-benzoselenazoles was assessed using a thiophenol assay, exhibiting greater antioxidant activity than Ph2Se2 used as a reference. The most active catalyst carrying a strong electron-donating group (-NMe2) at the ortho-position to the benzoselenazole ring was further investigated at different concentrations of thiophenol, H2O2, and 1,3-benzoselenazoles as catalyst for determining their catalytic parameters. Moreover, the potential applications of all 1,3-benzoselenazoles against pancreatic lipase (PL) have been identified using in silico interactions between the active sites of the 1LPB protein as evaluated using a molecular docking study.

Synthesis of 4-Alkylated 1,4-Dihydropyridines: Fe(II)-Mediated Oxidative Cascade Cyclization Reaction of Cyclic Ethers with Enaminones

Syntheses of highly functionalized 4-alkylated 1,4-dihydropyridines (1,4-DHPs) from cyclic ethers and enaminones via iron(II)-mediated oxidative free radical cascade C(sp3)-H bond functionalization/C(sp3)-O bond cleavage/cyclization reaction have been first developed. This novel synthetic strategy offers an alternative method for the construction of 1,4-DHPs by using esters as the C4 sources, as well as expands the application of ethers in heterocycle synthesis.

Synthesis of 2-Fluoroalkylated Oxazoles from β-Monosubstituted Enamines via Fluoroacyloxylation and Cyclization Mediated by Fluoroalkyl-Containing Hypervalent Iodine(III) Species Generated In Situ

A metal-free synthesis of a series of fluoroalkyl-containing oxazoles from β-monosubstituted enamines was developed. This fluoroacyloxylation/cyclization cascade process was mediated by fluoroalkyl-containing hypervalent iodine(III) species formed in situ from the reaction of phenyliodine(III) diacetate (PIDA) and RCF₂CO₂H (R = H, Cl, Br, F, CF₃, CH₃, Ph, SAr, OAr).

Rongalite as C1 Synthon in the Synthesis of Divergent Pyridines and Quinolines

Rongalite has been used as a cheap and efficient carbon synthon for the synthesis of divergent N-heteroaromatics, including different pyridines and quinolines. The selective synthesis of different products can be achieved by employing enaminones or enaminones/anilines as reaction partners. In addition, compared with the reaction using conventional aldehyde synthons, rongalite displays an evident advantage in providing products with considerably higher product yields under milder conditions. The GC-MS analysis of the reaction process has been performed to probe the possible reaction mechanism.

Recent progress of direct thiocyanation reactions

Thiocyanates are common in natural products, synthetic drugs and bioactive molecules. Many thiocyanate derivatives show excellent antibacterial, antiparasitic and anticancer activities. Thiocyanation can introduce SCN groups into parent molecules for constructing SCN-containing small organic molecules. Among them, the direct introduction method mainly includes nucleophilic reaction, electrophilic reaction and free radical reaction, which can simply and quickly introduce SCN groups at the target sites to construct thiocyanates, and has broad application prospects. In this review, we summarize the research progress of direct thiocyanation in recent years.