Enantioselective Synthesis of Oasomycin A, Part I: Synthesis of the C1-C12 and C13-C28 Subunits

Putting the pieces together: The total synthesis of the natural macrolide oasomycin A has been realized. Key fragment couplings include an anti‐Felkin selective aldol addition (green), Kociensky–Julia olefinations (red), and competitive Weinreb amide acylation reaction (blue). The utility of the 4,5‐diphenyloxazole as a carboxy surrogate and the late‐stage macrolactonization affording the 42‐membered macrocycle of oasomycin A are also described.