Scheme 1. Synthesis of PTL derivatives 2 (tertiary amines), 3 (a thioether), 4 (acyclic secondary amines), 5 (cyclic tertiary amines) and 6 (amino acid derivatives). Two protocols: Conditions (i) – Addition of nucleophile in ethanol at room temperature; conditions (ii) – addition of nucleophile in dimethylsulphoxide/methanol (20/80) with Hünig's base at room temperature. All product R1 and R2 groups shown in Fig. 3.
