PIDA-mediated oxidative aromatic C N bond cleavage: Efficient methodology for the synthesis of 1,2-diaza-1,3-dienes under ambient conditions

Silver-Catalyzed Synthesis of 5-Amino-4-sulfonyl Pyrazoles from 1,2-Diaza-1,3-dienes

A facile and dependable synthetic route for 5-amino-4-sulfonyl pyrazoles, which are substantially important in pharmaceuticals, is highly desirable. This work presents a novel cascade reaction for their efficient synthesis. The approach utilizes silver as a catalyst for C(sp2)-H sulfonylation of readily available starting materials 1,2-diaza-1,3-dienes with sulfinate salts, followed by intramolecular cascade cyclization annulation to afford the desired 5-amino-4-sulfonyl pyrazoles in good to excellent yields under mild conditions.

Recent Progress in Synthetic Applications of Hypervalent Iodine(III) Reagents

Hypervalent iodine(III) compounds have found wide application in modern organic chemistry as environmentally friendly reagents and catalysts. Hypervalent iodine reagents are commonly used in synthetically important halogenations, oxidations, aminations, heterocyclizations, and various oxidative functionalizations of organic substrates. Iodonium salts are important arylating reagents, while iodonium ylides and imides are excellent carbene and nitrene precursors. Various derivatives of benziodoxoles, such as azidobenziodoxoles, trifluoromethylbenziodoxoles, alkynylbenziodoxoles, and alkenylbenziodoxoles have found wide application as group transfer reagents in the presence of transition metal catalysts, under metal-free conditions, or using photocatalysts under photoirradiation conditions. Development of hypervalent iodine catalytic systems and discovery of highly enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important recent achievement in the field of hypervalent iodine chemistry. Chemical transformations promoted by hypervalent iodine in many cases are unique and cannot be performed by using any other common, non-iodine-based reagent. This review covers literature published mainly in the last 7-8 years, between 2016 and 2024.

Silver-catalyzed decarboxylative cyclization for the synthesis of substituted pyrazoles from 1,2-diaza-1,3-dienes and α-keto acids

A silver-catalyzed decarboxylative cyclization process has been developed for the synthesis of substituted pyrazoles from the readily available 1,2-diaza-1,3-dienes and α-keto acids. Under the optimized conditions, a series of multisubstituted pyrazoles were well prepared in moderate to good yields. In addition, the synthetic utility of this protocol has been demonstrated by synthesizing analogs of FDA approved drugs such as anti-inflammatory drug, lonazolac and antiobesity drug, rimonabant.