Synthesis and Metal-templated Assembly of Oxazole and Thiazole-based Amino Acids. Total Synthesis of Nostocyclamide and Related Cyclic Peptides

All articles of this category The oxazole and the thiazole-based amino acids, 3 - 5 , undergo cyclisation in the presence of FDPP, producing the natural hexapeptide nostocyclamide 2 and equal amounts of the analogues, 6 , 7 and 8 , in a combined yield of 65%. In the presence of Cu 2 + ions only a 2 : 1 mixture of nostocyclamide and the cyclic peptide 6 results, and proportions of 2 are also enhanced when Li + or Ca 2 + ions are present. Likewise, the amount of the cyclic peptide 7 increases dramatically when the three amino acids 3 , 4 and 5 are mixed with FDPP in the presence of Na + or K + ions and in the presence of Ag + ions it is the sole cyclic peptide product. oxazole - thiazole - amino acids - nostocyclamide - cyclic peptides