Remote difunctionalization of 2H-indazoles using Koser's reagents

Abstract

A new, efficient, and metal-free protocol has been developed for remote difunctionalization of unreactive CH bonds at the benzene core of 2H-indazole by employing Koser’s reagents which act as both...

Recent advances in C–H functionalization of 2H-indazoles

“…Very recently, Hajra and co-workers developed a remote difunctionalization of unreactive C–H bonds of the benzene ring in 2 H -indazole using Koser's reagents as both sulfonyloxylating and iodinating reagents under mild and metal-free conditions (Scheme 52). 76 A variety of 7-iodo-4-sulfonyloxyl 2 H -indazoles were obtained with high regioselectivity in good to excellent yields. Mechanistically, under acidic conditions, Koser's reagent gives a phenyl tosyloxyiodonium intermediate, which is attacked by 2 H -indazole at the electrophilic iodine center to form cationic intermediate 52A .…”

Recent advances in carbosilylation of alkenes and alkynes

“…Our group has also made substantial contributions to the field of C-Si chemistry [34][35][36][37] as well as difunctionalization methodology. [38][39][40][41][42] In our ongoing research on the chemistry of C-Si bond formation, we present here a systematic review on carbosilylation of alkene and alkyne systems. In this perspective, we cover all the carbosilylated articles published between 2012 and 2022 in chronological order.…”

Origin of Ligand and Acid Effects on the Pd-Catalyzed Regiodivergent Coupling Reaction of Indazoles and Isoprene: A DFT Study

“…Indazoles are important building blocks found in various pharmaceuticals and biologically important molecules due to their biological and chemical activities. − Given their importance as privileged scaffolds in medicinal chemistry, diversely substituted indazole derivatives with different functional groups have received significant attention in recent years, and a large number of synthetic methodologies available in the literature for the functionalization of indazoles have been extensively studied. − The alkylation of indazoles represents one of the most efficient methods in terms of atom- and step-economy. , The transition metal catalyst has been designed as an effective tool for controllable selective functionalization in the alkylation of indazoles. Previous findings have shown that both rhodium and palladium could promote the coupling of N-substituted indazole with allenes for the synthesis of medicinally important targets. , However, due to the competitive nucleophilic sites between the N 1 and N 2 of indazoles, a mixture of N 1 - or N 2 -isomers is delivered normally under basic conditions. , Despite the fact that significant advances have been achieved in these pioneering works, the discovery of efficient catalysis for the selective N-allylation of indazoles is very limited. , Therefore, understanding how to obtain the desired product by regulating the competition for nucleophilic sites between the N 1 and N 2 positions of indazole is crucial for its development in this field. ,, …”