DIRECT SYNTHETIC APPROACH TO N-SUBSTITUTED 1-AMINO-2,3-DIHYDRO-1H-IMIDAZOLE-2-THIONES

In an efficient one-pot procedure, the title compounds (8) were obtain ed by the reaction of alpha-halo ketones (1) with potassium thiocyanat e and monosubstituted hydrazines (3). The reaction is considered to pr oceed via the formation of azo-alkenes (5) and thiocyanic acid. These intermediates, in turn, undergo a [3+2] cycloaddition reaction; the re sultant azomethine imine cycloadducts (6) are transformed into the fin al products (8). The structure of compounds (8) has been confirmed by utilization of various NMR techniques.