Synthesis of 1,3-selenazolies and bis(selenazoles) from primary selenocarboxylic amides and selenourea

The reaction of nitrites with P2Se5 in the presence of EtOH-H2O afforded primary selenocarboxylic amides. The cyclization of these compounds with alpha-halo ketones afforded a variety of functionalized 1,3-selenazoles. The use of P2Se5 also allowed the convenient synthesis of selenocarboxylic diamides which were transformed into bis(selenazol-2-yl)alkanes ('bis-selenazoles'). A practical method for the synthesis of selenourea was developed. This useful small building block was successfully applied to the synthesis of primary 2-amino-1,3-selenazoles.