Metal-free synthesis of 2-aminobenzoxazoles using hypervalent iodine reagent
作者:Yogesh S. Wagh、Neelam J. Tiwari、Bhalchandra M. Bhanage
DOI:10.1016/j.tetlet.2012.12.127
日期:2013.3
A facile, simple, mild, and metal-free protocol for the synthesis of 2-aminobenzoxazoles has been developed via C–H bond amination of benzoxazoles with amines through a ring-opening and subsequent ring-closure approach. The reaction was performed in two steps wherein nucleophilic addition of amines across benzoxazoles takes place in the absence of any reagent or catalyst under solvent-free condition
Metal-free N-iodosuccinimide-catalyzed mild oxidative C–H bond amination of benzoxazoles
作者:Yogesh S. Wagh、Dinesh N. Sawant、Bhalchandra M. Bhanage
DOI:10.1016/j.tetlet.2012.04.117
日期:2012.7
facile, efficient, and mild protocol for the synthesis of aminobenzoxazoles has been developed using direct oxidative C–H bond amination of benzoxazoles with secondary or primary amines. The reaction was performed using catalytic amount of N-iodosuccinimide and aqueous hydrogen peroxide as a green oxidant and in the absence of transition metals. Reaction proceeds smoothly at ambient temperature and
An efficient copper-catalyzed electrophilic amination of benzoxazoles with O-benzoyl hydroxylamines is described, employing CuCl catalyst, PPh3 ligand, and (LiOBu)-Bu-t base. This simple air-stable copper catalysis enables the preparation of various 2-aminobenzoxazole derivatives at room temperature in good yields. (C) 2013 Elsevier Ltd. All rights reserved.
Cu(acac)2 catalyzed oxidative C–H bond amination of azoles with amines under base-free conditions
作者:Yogesh S. Wagh、Bhalchandra M. Bhanage
DOI:10.1016/j.tetlet.2012.09.064
日期:2012.11
This work reports a simple and efficient methodology for oxidative C-H bond amination of azoles with aromatic/aliphatic amines using copper-bis-acetylacetonate complex catalyst. The catalyst works very well in the absence of external acid or base and requires only molecular oxygen as an oxidant. The methodology is applicable for the oxidative C-H bond amination of various azoles with different types of aromatic/aliphatic amines for the synthesis of various aminoheterocycles with good to excellent yields. (C) 2012 Elsevier Ltd. All rights reserved.