Lanthanide-catalyzed cyclocarbonylation and cyclothiocarbonylation: a facile synthesis of benzannulated 1,3-diheteroatom five- and six-membered heterocycles
La[N(SiMe3)2]3 proves to be an efficient catalyst system for the cyclocarbonylation of 1,2-disubstituted benzenes with isocyanates. In this approach, aryl/alkyl isocyanates react with o-phenylenediamine, o-aminophenol, o-aminothiophenol, catechols and anilines ortho-substituted by CH2NH2 and CONH2 to form, respectively, the corresponding benzimidazolones, benzoxazolones, benzothiazolones, benzodioxolones, 3,4-dihydroquinazolin-2(1H)-one, and quinazolinediones. These results represent the first example of lanthanide-catalyzed carbonylation. This methodology is also applicable for the preparation of various benzannulated 1,3-diheteroatom cyclic thioketones starting from aryl/alkyl isothiocyanates or CS2 in good to excellent yields. Based on the results of experiments performed using an o-aminobenzamido dianion lanthanide complex, a general mechanism, involving the tandem reaction of two lanthanide-ligand bonds with one heterocumulene molecule, is proposed as well.
An economically and environmentally sustainable synthesis of 2-aminobenzothiazoles and 2-aminobenzoxazoles promoted by water
作者:Xinying Zhang、Xuefei Jia、Jianji Wang、Xuesen Fan
DOI:10.1039/c0gc00418a
日期:——
Tandemreactions of isothiocyanates (1) with 2-aminothiophenols (2), or isothiocyanates (1) with 2-aminophenols (4), were carried out rapidly and efficiently in water. A significant rate acceleration of the reaction between 1a and 2a in water compared with commonly used volatile organic solvents was observed. Through these reactions, a variety of structurally and pharmaceutically interesting 2-aminobenzothiazoles
A novel, convenient and efficient protocol for the construction of various 2-aminophenyl benzothiazoles by domino intra- and intermolecular C–N cross-coupling reactions of arylisothioureas with aryl iodides using an inexpensive, air stable and readily available copper catalyst is described. The arylisothioureas were obtained from thiourea via copper promoted desulfurization followed by nucleophilic
Abstract A simple route for the synthesis of 2-aminophenyl benzothiazole through domino intra and inter molecular C-N cross-coupling reaction using a cobalt catalyst under mild reaction conditions has been accomplished. The procedure is experimentally simple, general, and efficient. All the substrates readily carried out under optimized reaction conditions to provide target products in moderate to
Iron-Catalyzed Tandem Reactions of 2-Halobenzenamines with Isothiocyanates Leading to 2-Aminobenzothiazoles
作者:Jing-Wen Qiu、Xing-Guo Zhang、Ri-Yuan Tang、Ping Zhong、Jin-Heng Li
DOI:10.1002/adsc.200900450
日期:2009.10
A highly practical method for the synthesis of 2-aminobenzothiazoles has been developed through an iron-catalyzed tandemreaction. The present tandem process allows the assembly of a wide range of 2-aminobenzothiazoles by the reactions of 2-halobenzenamines with isothiocyanates.