ChemInform Abstract: Organotin‐Based Bifunctional Reagents: 4‐Chloro‐2‐lithio‐1‐butene and Related Substances. Methylenecyclopentane Annulations. Total Synthesis of (.+‐.)‐δ9(12)‐Capnellene.

Abstract Lithiation of the stannylbutene (I) leads to the title lithiobutene which acts as a bifunctional reagent in the reaction with the compounds (II) and (IV).