Developments in Pd Catalysis: Synthesis of 1H-1,2,3-Triazoles from Sodium Azide and Alkenyl Bromides

Azide-free cyclization reaction access to 4-aryl-NH-1,2,3-triazoles: P-toluenesulfonyl hydrazide and sulfamic acid as nitrogen sources

An iodine-mediated cyclization has been developed to 4-aryl-NH-1,2,3-triazoles, with p-toluenesulfonyl hydrazide and sulfamic acid used as nitrogen sources. Sulfamic acid plays a crucial role in this reaction by both acting as a substrate and providing an acidic environment. This reaction offers a metal- and azide-free strategy to access NH-1,2,3-triazoles.

A comprehensive review of sources of nitrosamine contamination of pharmaceutical substances and products

N-nitrosamines are carcinogenic impurities most commonly found in groundwater, treated water, foods, beverages and consumer products. The recent discovery of N-nitrosamines in pharmaceutical products and subsequent recalls pose a significant health risk to patients. Initial investigation by the regulatory agency identified Active Pharmaceutical Ingredients (API) as a source of contamination. However, N-nitrosamine formation during API synthesis is a consequence of numerous factors like chemistry selection for synthesis, contaminated solvents and water. Furthermore, apart from API, N-nitrosamines have also been found to embed in the final product due to degradation during formulation processing or storage through contaminated excipients and printing inks. The landscape of N-nitrosamine contamination of pharmaceutical products is very complex and needs a comprehensive compilation of sources responsible for N-nitrosamine contamination of pharmaceutical products. Therefore, this review aims to extensively compile all the reported and plausible sources of nitrosamine impurities in pharmaceutical products. The topics like risk assessment and quantitative strategies to estimate nitrosamines in pharmaceutical products are out of the scope of this review.

Small Library of Triazolyl Polyphenols Correlating Antioxidant Activity and Stability with Number and Position of Hydroxyl Groups

Polyphenolic compounds have attracted much interest because of their antioxidant properties and multiple applications, from food or cosmetic preservatives to free radical scavengers as therapeutic agents. Inspired by common OH substitutions in natural products, here we describe a small library of 1,2,3-triazoles disubstituted with polyphenol groups at 1,4-positions, in an attempt to correlate the number and position of hydroxyl groups in the aromatic rings with the antioxidant activity. Some compounds from this library exhibit strong radical scavenging activities in the oxygen radical absorbance capacity assay, similar to or even higher than resveratrol and other well-kwon flavonoids. The antioxidant activity for selected compounds was confirmed in vitro through the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) test and in vivo by a Saccharomyces cerevisiae model organism assay. The activity depends on the number and position of the hydroxyl groups, with compounds bearing a 2″5″-hydroxyl substituents on the phenyl ring at position 4 showing the best antioxidant values. The presence of two quinone-forming phenolic groups at the same molecule is behind the instability of some of these compounds in aqueous media.

Metal-free C-N- and N-N-bond formation: synthesis of 1,2,3-triazoles from ketones, N-tosylhydrazines, and amines in one pot

A novel synthetic approach toward 1,4-disubstituted 1,2,3-triazoles by C-N- and N-N-bond formation has been established under transition-metal-free conditions. Complete control of the regioselectivity was successfully achieved. Commercially available anilines, ketones, and N-tosylhydrazine were treated with molecular iodine in one pot to allow the regioselective generation of 1,4-disubstituted 1,2,3-triazoles in high yields without the use of azides.

An organocatalytic azide-aldehyde [3+2] cycloaddition: high-yielding regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles

An organocatalytic azide-aldehyde [3+2] cycloaddition (organo-click) reaction of a variety of enolizable aldehydes is reported. The organo-click reaction is characterized by a high rate and regioselectivity, mild reaction conditions, easily available substrates with simple operation, and excellent yields with a broad spectrum of substrates. It constitutes an alternative to the previously known CuAAC, RuAAC, and IrAAC click reactions.