One-pot synthesis of N-substituted benzannulated triazoles via stable arene diazonium salts.

A mild and effective one-pot synthesis of 1,2,3-benzotriazin-4(3H)-ones and benzothiatriazine-1,1(2H)-dioxide analogues has been developed. The method involves the diazotisation and subsequent cyclisation of 2-aminobenzamides and 2-aminobenzenesulfonamides via stable diazonium salts, prepared using a polymer-supported nitrite reagent and p-tosic acid. The transformation was compatible with a wide range of aryl functional groups and amide/sulfonamide-substituents and was used for the synthesis of pharmaceutically important targets. The synthetic utility of the one-pot diazotisaton-cyclisation process was further demonstrated with the preparation of an α-amino acid containing 1,2,3-benzotriazin-4(3H)-one.

One-pot ortho-amination of aryl C-H bonds using consecutive iron and copper catalysis.

A one-pot approach for ortho-coupling of arenes with non-actived N-nucleophiles has been developed using sequential iron and copper catalysis. Regioselective ortho-activation of anisoles, anilines and phenols was achieved through iron(iii) triflimide catalysed iodination, followed by a copper(i)-catalysed, ligand-assisted coupling reaction with N-heterocycle, amide and sulfonamide-based nucleophiles. The synthetic utility of this one-pot, two-step method for the direct amination of ortho-aryl C-H bonds was demonstrated with the late-stage functionalisation of 3,4-dihydroquinolin-2-ones. This allowed the preparation of a TRIM24 bromodomain inhibitor and a series of novel analogues.

Multibond Forming Tandem Reactions of Anilines via Stable Aryl Diazonium Salts: One-Pot Synthesis of 3,4-Dihydroquinolin-2-ones.

A fast and effective one-pot tandem process that generates Heck coupled products from readily available anilines via stable aryl diazonium tosylate salts was developed. The mild and simple procedure involves rapid formation of aryl diazonium salts using a polymer-supported nitrite reagent and p-tosic acid, followed by a base-free Heck-Matsuda coupling with acrylates and styrenes. Using 2-nitroanilines as substrates, the one-pot tandem process was extended for the direct synthesis of 3,4-dihydroquinolin-2-ones. In this case, following diazotization and Heck-Matsuda coupling to give methyl cinnamates, addition of hydrogen and reutilization of the palladium catalyst for reduction of the nitro group and hydrogenation of the alkene resulted in efficient formation of 3,4-dihydroquinolin-2-ones. The synthetic utility of this one-pot, four-stage process was demonstrated with the five-pot synthesis of a quinolinone-based sodium ion channel modulator.

One-Pot Asymmetric Synthesis of Alkylidene 1-Alkylindan-1-ols Using Brønsted Acid and Palladium Catalysis.

A one-pot catalytic enantioselective allylboration/Mizoroki-Heck reaction of 2-bromoaryl ketones has been developed for the asymmetric synthesis of 3-methyleneindanes bearing a tertiary alcohol center. Brønsted acid-catalyzed allylboration with a chiral BINOL derivative was followed by a palladium-catalyzed Mizoroki-Heck cyclization, resulting in selective formation of the exo-alkene. This novel protocol provides a concise and scalable approach to 1-alkyl-3-methyleneindan-1-ols in high enantiomeric ratios (up to 96:4 er). The potential of these compounds as chiral building blocks was demonstrated with efficient transformation to optically active diol and amino alcohol scaffolds.