A general synthetic route towards bastadins. Part 2: Synthesis of the western part of bastadins 4-16, and fully functionalized macrocycle of bastadin 12

A general synthetic route for the construction of the western part of the macrocyclic bastadins 4-16 is presented. The western and the eastern segments were coupled using the imidazolide of the corresponding acid. The bromine at position Y-2 may be added at this advanced step regiospecifically, strengthening the convergence of the presented approach. Finally, the fully functionalized alpha,omega-aminoacid is cyclized with EDC affording the macrocyclic ring of bastadin-12 in 72% yield (3.5% overall yield). (C) 1999 Elsevier Science Ltd. All rights reserved.