- Lanthanide-catalyzed cyclocarbonylation and cyclothiocarbonylation: A facile synthesis of benzannulated 1,3-diheteroatom five- and six-membered heterocycles
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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.
- Jing, Yufeng,Liu, Ruiting,Lin, Yanghui,Zhou, Xigeng
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p. 1117 - 1125
(2014/08/18)
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- A Facile Synthesis of 8-Arylamino- and 8-Hetarylaminopurines and their 1- and 3-Deaza Analogs
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A general method for the synthesis of 8-arylamino- and 8-(2-benzothiazolylamino)-purines and their 1- and 3-deaza analogs is reported.The need for the presence of the desulfurizing agent in the preparation of the 8-arylamino derivatives is demonstrated an
- Garin, J.,Melendez, E.,Merchan, F. L.,Tejero, T.
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p. 867 - 870
(2007/10/02)
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