Total synthesis of kasichelins A and B.

The first total synthesis of kasichelins A and B was accomplished in a concise manner via a longest linear sequence of seven steps with 25% and 18% overall yields, respectively. The synthetic route featured a judicious choice of protecting groups, a molybdenum-promoted dehydrative cyclization for construction of the dihydrooxazole core, and a convergent fragment assembly strategy to forge the complete molecular scaffold.