Ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate 1 was used as a starting material to synthesize 2a-c via coupling with acetyl acetone, ethylcyanoacetate or malononitrile, respectively. Heating under reflux in sodium ethoxide solution 2a-c gave 3a-c. When compounds 3a-c were heated under reflux in ethanol with hydrazine hydrate, thiourea or 1,2-diaminoethane and a catalytic amount of piperidine to produce the spiro compounds 4a-c, 5a-c and 6, respectively.