A convergent, complementary, synthetic approach to the contiguously linked tris-oxazole units 10, 11 and 12 in telomestatin (1) and YM-216391 (2) is described. The route involves coupling reactions between oxazole 4-carboxylic acids, viz16a, 16c, 16d and oxazole 2- substituted methylamines, viz16b, 16e, 17, leading to the amides 18 and 21, followed by cyclodehydrations to the corresponding bis-oxazole oxazolines, eg 19, and oxidations of ...
