The reaction of nitriles with P 2 Se 5 in the presence of EtOH-H 2 O afforded primary selenocarboxylic amides. The cyclization of these compounds with a-halo ketones afforded a variety of functionalized 1,3-selenazoles. The use of P 2 Se 5 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.
Two new and efficient methods for the synthesis of 2unsubstituted 1,3-selenazoles, the fragmentation of 2-benzoyl-1,3selenazoles and the cyclization of a-bromoketones with selenoformamide, are reported.
Durch Addition von Acylhydrazinen an Aryl‐ oder Alkyl‐ bzw. Acyl‐isoselenocyanate werden in guten Ausbeuten 1,4‐disubstituierte Selenosemicarbazide gebildet. Die aus Selenosenfölen mit 4‐Aryl‐selenosemicarbaziden primär erhältlichen Hydrazin‐N, N′‐bis‐selenocarbonsäureamide cyclisieren meist gleich zu 2,5‐Diamino‐1,3,4‐selenadiazol‐Derivaten.
Aryl-isoselenocyanate ( l a ~ f) lassen sich in guter Ausbeute durch Anlagerung von elementarem Selen an Aryl-isocyanide herstellen. Sie weisen im IR-Spektrum eine charakteristische Bande auf, die zu ihrer ldentifizierung dienen kann. E. Frederiksen, 2. anorg. allg. Chem. 230, 31 (1936). 4) 4a) R. Huls und M. Renson, Bull. SOC. chim. belges 65, 684 (1956); 4b) C. Collard-Charon C. CoZlard-Charon und M. Renson, ebenda 72,
3) K. A. Jensen und
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