ZnAl2O4–Bi2O3 composite nano-powder as an efficient catalyst for the multi-component, one-pot, aqueous media preparation of novel 4H-chromene-3-carbonitriles

Tetrazol-Cu(i) immobilized on nickel ferrite catalyzed green synthesis of indenopyridopyrimidine derivatives in aqueous media

After the initial study of different protocols in the synthesis of indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidines, herein, a new method is presented using cheaper and more accessible starting materials to produce high-efficiency products. In this protocol, the novel nanocatalyst is very effective in the progression of the reaction and increasing the efficiency. This green approach in aqueous media has several advantages as compared with other methods, such as easier work-up, very mild reaction conditions, reusability of the catalyst, and eco-friendliness. The products of this four-component condensation were evaluated using IR, ¹H NMR, ¹³C NMR spectra, and C. H. N. analyses, and the catalyst structure was confirmed by FT-IR, XRD, SEM, EDX, TGA and VSM techniques.

In this protocol, a novel nanocatalyst was very effective in progression of the reaction and increasing efficiency. This green approach in aqueous media has several advantages compared with the reported methods.

Near-infrared nerve-binding fluorophores for buried nerve tissue imaging

Nerve-binding fluorophores with near-infrared (NIR; 650 to 900 nm) emission could reduce iatrogenic nerve injury rates by providing surgeons precise, real-time visualization of the peripheral nervous system. Unfortunately, current systemically administered nerve contrast agents predominantly emit at visible wavelengths and show nonspecific uptake in surrounding tissues such as adipose, muscle, and facia, thus limiting detection to surgically exposed surface-level nerves. Here, a focused NIR fluorophore library was synthesized and screened through multi-tiered optical and pharmacological assays to identify nerve-binding fluorophore candidates for clinical translation. NIR nerve probes enabled micrometer-scale nerve visualization at the greatest reported tissue depths (~2 to 3 mm), a feat unachievable with previous visibly emissive contrast agents. Laparoscopic fluorescent surgical navigation delineated deep lumbar and iliac nerves in swine, most of which were invisible in conventional white-light endoscopy. Critically, NIR oxazines generated contrast against all key surgical tissue classes (muscle, adipose, vasculature, and fascia) with nerve signal-to-background ratios ranging from ~2 (2- to 3-mm depth) to 25 (exposed nerve). Clinical translation of NIR nerve-specific agents will substantially reduce comorbidities associated with surgical nerve damage.

Synthesis and pharmacological properties of polysubstituted 2-amino-4H-pyran-3-carbonitrile derivatives

2-Amino-3-cyano-4H-chromenes are structural core motifs that received increasing attention in the last years due to their interesting potential pharmacological properties. In this review, the synthetic methods for these compounds are classified based on the type of catalyst in the pertinent reactions. In addition, the wide range of pharmacological properties of these compounds is covered in a separate section.

Green Chemistry Preparation of thiochromeno[4,3-b]pyran and benzo[h]thiazolo[2,3-b]quinazoline Derivatives using HSBM Technique over ZnAl2O4 Nano-Powders

AIM AND OBJECTIVE

The aim of this paper is to introduce HSBM as a green and environmentally friendly technique for the synthesis of thiochromeno[4,3-b]pyran and benzo[h]thiazolo[2,3-b]quinazoline derivatives over ZnAl2O4 nanopowders as an efficient catalyst.

MATERIALS AND METHODS

ZnAl2O4 nanopowders were synthesized via a co-precipitation of Zn(NO3)2 and Al(NO3)3 salts and were characterized by XRD, FE-SEM, TEM and DLS techniques. The as-prepared ZnAl2O4 nano-powders have been used as a catalyst on the synthesis of pyran nucleus using high-speed ball milling (HSBM) technique. The structure of products was confirmed with NMR analysis.

RESULTS

ZnAl2O4 exhibits a cubic crystal structure (Space group: Fd-3m) with the average crystallite size of 41 nm. The average particle size of ZnAl2O4 nano-powders determined by DLS technique is 55 nm. The catalytic activity of nano-powders was examined on the synthesis of 2- amino-4,5-dihydro-4-arylthiochromeno[4,3-b]pyran-3-carbonitriles, (8Z)-2-amino-8-arylidene-4,5, 7,8-tetrahydro-4-arylthiopyrano[4,3-b]pyran-3-carbonitriles, 4-aryl-3,4,5,6-tetrahydrobenzo[h]quinazoline- 2(1H)-thiones and 4-aryl-1,3,4,5-tetrahydro-2H-thiochromeno[4,3-d]pyrimidine-2-thione derivatives. All products were obtained in high yields with short reaction times.

CONCLUSION

ZnAl2O4 nanopowders were prepared via a cost-effective co-precipitation method and showed good potential for the synthesis of 4H-pyran analogous in good yields. The salient advantages of HSBM technique include environmentally friendly with reduced solvents, is a simple technique and has low energy costs.

Solvent-free preparation of 3-aryl-2-[(aryl)(arylamino)]methyl-4H-furo[3,2-c]chromen-4-one derivatives using ZnO-ZnAl2O4 nanocomposite as a heterogeneous catalyst

The title compounds were synthesized by a three-component reaction of 4-hydroxycoumarin, aromatic amines and α,β-epoxy ketones, catalyzed by ZnO-ZnAl2O4 nanocomposite.