Synthesis and Biological Activity of Kalkitoxin and its Analogues

Abstract

Total syntheses of kalkitoxin, isolated from the Caribbean <i>Lyngbya majuscula</i>, and its analogues, 3-<i>epi</i>-, 7-<i>epi</i>-, 8-<i>epi</i>-, 10-<i>epi</i>-, 10-<i>nor</i>-, and 16-<i>nor</i>-kalkitoxin, were achieved via oxazolidinone-based diastereoselective 1,4-addition reaction of a methyl group and efficient TiCl₄-mediated thiazoline ring formation as the key steps. The biological activities of synthetic kalkitoxin and its analogues were evaluated with brine shrimp