Acyclic and cyclic thioenamino peptides: solution- and solid-phase synthesis

Seven- and 10-membered cyclic thioenamino peptides, that is, 1,4-thiazepinone (11) and cyclic thioenamino peptide 9 (which represents a potential γ-turn mimetic), were synthesized, and the structure of 11 was secured by X-ray diffraction analysis of its TFA salt. The aforementioned compounds were prepared in solution and by solid-phase synthesis. Additionally, we have prepared thioenamino diketopiperazine synthon 16.