Convenient approach to ω-aminoalkylthiophenes
Tetrahedron Lett. 2016, 57 (17), 1909-1911
Starting from readily accessible cyclic enaminoesters, arylisothiocyanates and α-haloketones, a facile method for the synthesis of ω-aminoalkylthiophene hydrobromides was developed. It was shown that in the first step cyclic enaminoesters react with arylisothiocyanates exclusively at the enamine position. Upon treatment with base, free 5-aminopentylthiophenes were prepared. In the case of shorter alkyl substituents (4-aminobutyl and 3-aminopropyl) the free ω-aminoalkylthiophenes undergo intramolecular condensation of the amino and ketone groups affording novel fused heterocycles - thieno[2,3-c]azepine and thieno[2,3-c]azocine.