Solvent-Free Synthesis of Chiral N,N′-Disubstituted Thioureas by ‘Just Mixing’ the Reagents - Vázquez, Jaime; Bernès, Sylvain; Reyes, Yasmi; Moya, Mónica; Sharma, Pankaj; Alvarez, Cecilio; Gutiérrez, René (Synthesis, 2004)