LM-1554 is synthesized by condensation of 2-amino-3-carbethoxy-4,5,6,7-tetrahydrobenzo[b]thiophene (I) with chloroacetonitrile (III) in the presence of dry hydrogen chloride gas followed by basification. Alternatively, 2-amino-3-carbamoyl-4,5,6,7-tetrahydrobenzo[b]thiophene (IV) can be condensed with chloroacetonitrile (III) under the above reaction conditions. The condensation of (I) with chloroacetamide (II) in the presence of an equivalent of phosphorus oxychloride in chloroform followed by basification also yields LM-1554.
By reaction of 2-aminobenzophenones (I) with bromoacetyl halide (II) or tosyloxyacetyl halide (VI) to give, respectively, 2-(bromoacetylamino)benzophenones (III) or 2-(tosyloxyacetylamino)benzophenones (VII), which are treated with ethanolamine (IV) to give the compounds (V), which with acetic acid in ethanol give the desired compounds. These compounds can also be obtained from (III) and (VI) without isolation of (V)