Synthesis and aromatisation of cyclic enediyne-containing amino acids

A series of cyclic enediyne-containing amino acids with ring sizes varying from 10 to 12 atoms have been prepared starting from propargylglycine and homopropargylglycine. Their reactivity towards Bergman cyclisation under elevated temperatures has been explored. The enediynes displayed marked differences in cyclisation half-lives depending on the olefinic substituent and the ring size. A potential candidate for incorporation into peptides has been identified.