page_title: Ladderane
section_title: Dimerization of cyclobutadiene
hierarchical_section_title: Ladderane / Synthesis / Dimerization of cyclobutadiene
caption_attribution_description: English: Ladderane syntheses through cyclization
context_page_description: In chemistry, a ladderane is an organic molecule containing two or more fused cyclobutane rings. The name arises from the resemblance of a series of fused cyclobutane rings to a ladder. Numerous synthetic approaches have been developed for the synthesis of ladderane compounds of various lengths. The mechanisms often involve [2 + 2] photocycloadditions, a useful reaction for creating strained 4-membered rings. Naturally occurring ladderanes have been identified as major components of the anammoxosome membrane of the anammox bacteria Planctomycetes.
context_section_description: The dimerization of two cyclobutadienes can generate both the syn and anti ladderane products depending on the reaction conditions. The first step in forming the syn product involves the generation of 1,3-cyclobutadiene by treatment of cis-3,4-dichlorocyclobutene with sodium amalgam. The reactant passes through a metalated intermediate before forming 1,3-cyclobutadiene, which can then dimerize to form the syn-diene. Hydrogenation of the double bonds will form the saturated syn-[3]-ladderane.
  To generate the anti product, cis-3,4-dichlorocyclobutene is treated with lithium amalgam. The lithium derivative undergoes a C-C coupling reaction to produce the open dimeric structure. This intermediate reacts to form the anti-diene, which can be hydrogenated to form the final anti-[3]-ladderane product.
caption: Syntheses of ladderanes through cyclization
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