Oxidative desulfurization of disubstituted thioureas using Pb(II) salts and investigation of pKa-dependent regioselective N-acylation
摘要:
A highly efficient method for the N-acylation of both symmetrical and unsymmetrical thioureas by the use of lead (II) salts and triethylamine has been achieved. The reaction gives regioselective N-acylated product for unsymmetrical thiourea. For unsymmetrical thiuourea, regioselective N-acylation takes place towards the amine having lower pKa. A linear correlation between the pKas of the amines and the regioselective N-acylation is found. Another attractive feature of this transformation is that lead sulfide, which is important to material science, is obtained as a side product (nanocubes of 20nm).
Tandem synthesis of [1,2,4]-triazoles mediated by iodine—a regioselective approach
作者:Srimanta Guin、Saroj Kumar Rout、Nilufa Khatun、Tuhin Ghosh、Bhisma K. Patel
DOI:10.1016/j.tet.2012.04.042
日期:2012.6
A tandem regioselective one-pot synthesis of 3-amino-[1,2,4]-triazoles has been achieved from 1,3-disubstituted thioureas using molecular iodine. In this one-pot strategy, the intermediate carbodiimide generated in situ from thiourea upon reaction with HCONHNH2 gives diaryl/alkylhydrazinecarboximidamide or acylureidrazone, which then undergoes an intramolecular cyclodehydration to afford the corresponding 3-amino-[1,2,4]-triazole. The product regioselectivity for unsymmetrical 1,3-disubstituted thioureas correlate well with the pK(a)s of the parent amines attached, in which the amine having higher pK(a) goes to the ring nitrogen while the other nitrogen remains flanked as an exocyclic nitrogen of the triazole core. This method is milder and environmentally sustainable giving good to excellent yields of the desired products. (C) 2012 Elsevier Ltd. All rights reserved.
Anticonvulsant and cardiovascular effects of substituted thiazolidones
作者:S. Nagar、H. H. Singh、J. N. Sinha、Surendra S. Parmar
DOI:10.1021/jm00260a027
日期:1973.2
VASILEV, GEORGI NIKOLOV;VASILEV, NIKOLAJ GEORGIEV
作者:VASILEV, GEORGI NIKOLOV、VASILEV, NIKOLAJ GEORGIEV
Oxidative desulfurization of disubstituted thioureas using Pb(II) salts and investigation of p<i>K</i><sub>a</sub>-dependent regioselective N-acylation
作者:Harisadhan Ghosh、Soumya Sarkar、Abdur Rezzak Ali、Bhisma K. Patel
DOI:10.1080/17415990903295686
日期:2010.2
A highly efficient method for the N-acylation of both symmetrical and unsymmetrical thioureas by the use of lead (II) salts and triethylamine has been achieved. The reaction gives regioselective N-acylated product for unsymmetrical thiourea. For unsymmetrical thiuourea, regioselective N-acylation takes place towards the amine having lower pKa. A linear correlation between the pKas of the amines and the regioselective N-acylation is found. Another attractive feature of this transformation is that lead sulfide, which is important to material science, is obtained as a side product (nanocubes of 20nm).