Syntheses of a pyrrolidine analog of a tetrahydrofuran containing acetogenin, cis-solamin

Practical synthesis of a pyrrolidine analog of a mono-THF acetogenin as a proto-type analog to evaluate the effect of a heteroatom in the mono-THF ring of acetogenins was achieved using Pd(II)-catalyzed diastereo-selective cyclization. Ligand-less PdCl ₂ catalyzed cyclization yielded the desired pyrrolidine derivative as a single major product having the desired relative configurations. Coupling of the pyrrolidine fragment with a known γ-lactone-containing fragment via a Sonogashira cross-coupling reaction yielded the desired aza-cis-solamin analog.