Copper(I)-Catalyzed Cascade Synthesis of 2-Substituted 1,3-Benzothiazoles: Direct Access to Benzothiazolones
作者:Siva Murru、Pravat Mondal、Ramesh Yella、Bhisma K. Patel
DOI:10.1002/ejoc.200900711
日期:2009.11
An efficient cascade process for the preparation of 2-substituted 1,3-benzothiazoles directly from 2-haloaryl isothiocyanates and O or S nucleophiles by a Cu-catalyzed, intramolecular, C–S bond formation has been developed. This cascade method is viable for the efficient syntheses of both O- and S-substituted 1,3-benzothiazoles. Furthermore, 1,3-benzothiazol-2(3H)-ones having an alkyl group allow easy
Axially chiral N-(o-aryl)-2-thioxo-oxazolidine-4-one and rhodanine derivatives: enantiomeric separation and determination of racemization barriers
作者:Esra Müjde Yılmaz、İlknur Doğan
DOI:10.1016/j.tetasy.2008.09.001
日期:2008.9
Axially chiral 5,5-dimethyl-3-(o-aryl)rhodanine, 3-(o-aryl)rhodanine and 5,5-dimethyl-3-(o-aryl)-2-thioxo-4-oxazolidinone derivatives have been synthesized as racemates and the energy barriers to enantiomerization have been determined by dynamic H-1 NMR or by following the thermal equilibration of the separated enantiomers using chiral HPLC. The barriers to rotation about the N-sp2-C-aryl single bond were found to be 82-129 kJ/mol. The racemization barriers in these compounds are affected by the size of the ortho-substituent on the aryl ring. The magnitude of the barriers was found to change linearly with the van der Waals radii of the ortho-halogen substituents. (C) 2008 Elsevier Ltd. All Fights reserved.
Intra- and Intermolecular C−S Bond Formation Using a Single Catalytic System: First Direct Access to Arylthiobenzothiazoles
作者:Siva Murru、Harisadhan Ghosh、Santosh K. Sahoo、Bhisma K. Patel
DOI:10.1021/ol9017535
日期:2009.10.1
We have for the first time developed two ligand-assisted Cu(I)-catalyzed sequential intra- and intermolecular Sarylations leading to the direct synthesis of arylthiobenzothiazoles in one pot without an inert atmosphere. Low catalyst loading, inexpensive metal catalyst and ligand, lower reaction temperature, and shorter reaction times make this method superior to all reported methods for the synthesis of arylthiobenzothiazole.