Monocarbamates 2 have been prepared from 3,4-diaminothiophene 1 and were alkylated on the thiophene nucleus using an aldehyde and selenophenol, under acid catalysis. This reaction has allowed the access to 2-alkyl 3,4-diaminothiophenes 9, 3,5-diaminodithieno[3,2-b:2′,3′-e]pyridines 10 and l-alkyl thieno[3,4-d]imidazolones 13.