Convenient and Reliable Routes Towards 2‐Aminothiazoles: Palladium‐Catalyzed versus Copper‐Catalyzed Aminations of Halothiazoles

Abstract

Two efficient methods for the amination of 2-halothiazoles are presented here. A first protocol requires a Pd/L system. Several 2-aminothiazoles were synthesized under optimized conditions and isolated in good yields. The first palladium-catalyzed C À N coupling reactions between 2-halothiazoles and primary alkylamines are presented. In a second part, ligand-free copper-catalyzed aminations of 2-halothiazoles by alkylamines and aniline in a green solvent have been developed. The protocol is very ef-fective for primary and secondary amines and perfectly tolerates the presence of another halide moiety on the 2-halothiazole. The reaction occurs under the assistance of microwave irradiation, which drastically decreases the reaction time. The reaction leads to the formation of 2-aminothiazoles, key molecules in pharmaceutical research.

Lithium/Element Exchange as an Efficient Tool for Accessing Atropo-enriched Biaryls via Arynes

“…In contrast, in the second scenario, if the aryne approaches the carbon-lithium bond syn to the tBu group, the sulfinyl moiety would rotate 'counter-clockwise', forcing the tBu group to become pseudo-axial. application in the synthesis of monophosphine ligands for C-C and C-N coupling reactions, [17,20,46] diphosphines for asymmetric hydrogenation, [16,26] P-chirogenic derivatives, [15,18] phospholes [47] for hydroformylation as well as natural products like (-)-steganacin. [48,49] Actually, our group is now working on an enantioselective version.…”

Switchable and Scalable Heteroarylation of Primary Amines with 2-Chlorobenzothiazoles under Transition-Metal-Free and Solvent-Free Conditions

“…For instance, the C–N cross-coupling of 2-aminobenzothiazole (or its derivatives) with boronic acids, , aryl halides, − triflates, or triazenes efficiently afforded the aminated products. Besides, treatment of amines with unsubstituted benzothiazole − or 2-substituted benzothiazoles − also enabled the efficient formation of the desired products (Scheme a). It was observed that all of the above reactions went through one amination sequence to furnish the mono-heteroarylation products.…”

Copper‐catalyzed one‐pot coupling reactions of aldehydes (ketones), tosylhydrazide and 2‐amino(benzo)thiazoles: An efficient strategy for the synthesis of N‐alkylated (benzo)thiazoles

“…Considering the importance of 2‐ N ‐(alkylamino)azoles, a number of methods have been developed for their synthesis (Scheme ). The successful protocols for the synthesis of 2‐ N ‐(alkylamino)azoles involve aminations of halobenzothiazoles with alkylamines or cross‐coupling reactions between aminazoles and aryl halides, the direct oxidative couplings of azoles with amines or formamides, intramolecular cyclization of N ‐arylthioureas or ortho ‐halophenylthioureas, condensation of isothiocyanates with amines, Cu‐catalyzed condensation of sodium hydrosulfide with carbodiimide, Cu‐catalyzed/mediated three‐component condensation reactions, aerobic oxidative cyclization/dehydrogenation of thioureas and cyclohexanones and metal‐catalyzed N ‐alkylation of aminazoles with alcohols . Although the above procedures are generally practical and versatile, some of them still have various limitations such as the use of noble metals and additives, a longer reaction time, a limited substrate scope and the generation of many unwanted wastes.…”