A new synthetic route to Tyromycin A and its analogue from renewable resources

The synthesis of tyromycin A and that of the non-natural lower homologue, involving as featuring stepsa transition metal catalyzed atom transfer radical cyclization and a functional rearrangement of thepolyhalogenated 2-pyrrolidinones thus obtained, are described. Both routes use 10-undecenoic acid,a renewable source from castor oil, as starting material for the preparation of the pivotal intermediatesa,a,a0,a0-tetrachlorodicarboxylic acids.