Synthesis of 3-heteroalkyl-2-N-organylaminothiophenes.: The first proof for amino-imino tautomerism of N-monosubstituted aminothiophenes

The compounds 2-N-methylamino-3-methoxythiophene and 2-N-phenylamino-3-methoxythiophene obtained in fair to good yields in a novel one-pot synthesis from methyl or phenyl isothiocyanate and 1-lithiomethoxyallene have been shown to be in equilibrium with the imino tautomers. The analogous 3-methylthio derivatives obtained by a similar procedure from 1-lithiomethylthioallene exist exclusively in the amino form. (C) 1998 Elsevier Science Ltd. All rights reserved.