Abstract Trimeric tetrameric and pentameric oligolides are formed preferentially from (S)-?-butyrolactone or from methyl (R)-3-hydroxybutanoate upon prolonged treatment with catalytic amounts of tetraoxadistannacyclodecane (Shanzers macrolactonization catalyst) in refluxing xylene. The crystal structure of the tetramer is described. Substructures of the larger folded oligolides are used for the construction of a left-handed 21-helix as found in the biopolymer PHB and a heretofore unknown right-handed 31-helix. Source: https://www.artikelschreiber.com/en/.