One-Pot Fe-Catalyzed Pheromone Synthesis Via C1-Homologation of Unsymmetrical α,ω-Dihalogenated Derivatives with an Even Number of Carbon Atoms

We report in this work the optimization of a one-pot, four-step coupling sequence allowing stereoselective formation of alkyl-alkenyl linkages under iron catalysis at a low 0.25% load starting from difunctionalized electrophiles. A key tandem C1 homologation step followed by an iron-catalyzed Kumada alkyl-alkenyl cross-coupling is included in this sequence, allowing the direct obtention of an aliphatic nucleophile with an odd number of carbon atoms, bearing a terminal magnesium alkoxide function. The latter group acts as an in situ generated endogenous additive in the subsequent coupling step, bypassing the need for engineered ligands. Overall, this report affords a cheap and efficient way to generate odd-numbered coupling partners which usually request multistep preparation, along with their use in one-pot coupling syntheses using an Earth-abundant metal. Several applications to the obtention of targets of agrochemical interest are also described.