21427-52-1Relevant articles and documents
Cu(ii) catalysed chemoselective oxidative transformation of thiourea to thioamidoguanidine/2-aminobenzothiazole
Sahoo, Santosh K.,Khatun, Nilufa,Gogoi, Anupal,Deb, Arghya,Patel, Bhisma K.
, p. 438 - 446 (2013/04/10)
2-Haloaryl-sec-alkyl unsymmetrical thioureas (Tu) (halo = -F, -Cl) with a catalytic amount of Cu(ii) salt get oxidised in situ to their disulfide intermediates followed by an imine-disulfide rearrangement to give thioamidoguanidino (Tag) moieties at room temperature. During this process Cu(ii) gets reduced to Cu(i) and forms a complex with the Tag moiety from which Tag moiety can be isolated upon treatment with ammonia. However, when the same reaction was performed at an elevated temperature with a catalytic quantity of Cu(ii) salt, Tu bearing o-halogens (-F, -Cl) gave 2-aminobenzothiazoles via a dehalogenative heteroarylation path and not by the Hugerschoff path involving an electrophilic substitution reaction. For thioureas containing reactive ortho halogens (such as -Br, -I) the reaction proceeds at room temperature giving 2-aminobenzothiazoles via a dehalogenative path requiring a catalytic quantity of Cu(ii). No transformation of thiourea (Tu) to Tag was observed with Cu(i) salts suggesting the requirement of an oxidising Cu(ii) salt for this oxidative transformation. Mild reaction conditions, environmentally benign reagents and solvent, high yields, tolerance of various functional groups are some of the essential features of this methodology.
A model for a solvent-free synthetic organic research laboratory: Click-mechanosynthesis and structural characterization of thioureas without bulk solvents
Strukil, Vjekoslav,Igrc, Marina D.,Fabian, Laszlo,Eckert-Maksic, Mirjana,Childs, Scott L.,Reid, David G.,Duer, Melinda J.,Halasz, Ivan,Mottillo, Cristina,Friscic, Tomislav
supporting information, p. 2462 - 2473 (2013/02/21)
The mechanochemical click coupling of isothiocyanates and amines has been used as a model reaction to demonstrate that the concept of a solvent-free research laboratory, which eliminates the use of bulk solvents for either chemical synthesis or structural characterization, is applicable to the synthesis of small organic molecules. Whereas the click coupling is achieved in high yields by simple manual grinding of reactants, the use of an electrical, digitally controllable laboratory mill provides a rapid, quantitative and general route to symmetrical and non-symmetrical aromatic or aromatic-aliphatic thioureas. The enhanced efficiency of electrical ball milling techniques, neat grinding or liquid-assisted grinding, over manual mortar-and-pestle synthesis is demonstrated in the synthesis of 49 different thiourea derivatives. Comparison of powder X-ray diffraction data of mechanochemical products with structural information found in the Cambridge Structural Database (CSD), or obtained herein through single crystal X-ray diffraction, indicates that the mechanochemically obtained thiourea derivatives are pure in a chemical sense, but can also demonstrate purity in a supramolecular sense, i.e. in all structurally explored cases the product consisted of a single polymorph. As an extension of our previous work on solvent-free synthesis of coordination polymers, it is now demonstrated that such polymorphic and chemical purity of selected thiourea derivatives, the latter being evidenced through quantitative reaction yields, can enable the direct solvent-free structural characterization of mechanochemical products through powder X-ray diffraction aided by solid-state NMR spectroscopy.
