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 steps a transition metal catalyzed atom transfer radical cyclization and a functional rearrangement of the polyhalogenated 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 intermediates α,α,α′,α′-tetrachlorodicarboxylic acids.