Synthesis of different types of valerolactams starting from 2,5-dihydrooxazoles

Tricyclic valerolactams characterized by a variable heteroatom in γ-position, for example, sulfur, oxygen or nitrogen, were synthesized starting from 2,5-dihydrooxazoles. The chosen synthetic procedures included the addition of thiosalicylic acid as well as the addition of salicyl chloride. The nitrogen containing lactams were prepared in a cycloaddition and subsequent oxidation.