Preparation and Characterisation of Several New N-Disubstituted 2-Aminoselenophene Derivatives*

N,N -Persubstituted 3-aminothioacrylamides of the general structure 3 are well-known as versatile synthons in organic chemistry [1]. They are easily available by several different routes [2], e.g., from simple N-disubstituted acetamides 1 via corresponding 1-chlorovinamidinium salts 2 [3], and are highly reactive towards a lot of preferably electrophilic reagents which are able to transform these educts with their S-C-C-C moiety into a variety of products. For instance, they can be transformed, by reaction with halomethylcarbonyl compounds as well as with nitroor dicyanovinyl-substituted (het)arylmethyl halides, via corresponding 1-mercapto-substituted vinamidinium salts of the general structure 5, into 5-aceptor-substituted 2-aminothiophenes 7. Examples of the latter include 5acylor 5-alkoxycarbonyl-substituted 2-aminothiophenes [4], 5 -nitroor 5 -dicyanovinyl-substituted 5-amino-2,2 -bithiophenes and 4 -nitroor 4 -dicyanovinyl-substituted 5-phenyl-2-aminothiophenes [5]. Whereas the 5-acyland 5-alkoxycarbonylsubstituted 2-aminothiophenes raise some interest as starting materials for preparing deeply coloured methine dyes [6], the nitroand dicyanovinyl-sub-