Abstract The Gewald syntheses were employed to prepare a series of 2-amino-3- carboethoxythiophenes, and the syntheses of two of these, namely, the 3, 4-trimethylene (1f) and 3, 4-tetramethylene (1g) derivatives, were examined in detail. In two preparations of 1f, octahydro-6a-(4-morpholinyl)-2-thioxocyclopenta [b] pyrrole-3-carboxylic acid (7) was a co- product. The structure of 7 was ascertained from its 300 MHz 1 H nmr and 13 C nmr ...