Conformational analysis of the 14-membred unsymmetrical macrodiolides (m=2, n=4) has been carried out using hybrids molecular mechanics and quantum calculations at different levels. A new MM2 and MM3 torsional parameters of the missing 5-2-3-6 dihedral type were proposed. The results indicate that the C3-C2-C1-O3 dihedral can adopt both the s-trans and s-cis form, while the C10-C9-C8-O4 has a clear preference for the s-cis form. The same anti-dihedral angle C4-C5-C6-C7, around 150°, and gauche dihedral angle C10-C11-C12-O1, around 48°, characterize the conformational states of all the investigated compounds. The presence of substituents (including methyl groups), have a significant impact on the conformational behavior of the ring, leading (depending on its configuration) to favoring a certain type of conformations, like in the colletallol. In conjunction with that, the revise of cyclotetradecane conformational behavior, by the use of polar map, which is a convenient tool to identify and compare the conformations, reveal that it is richer on conformational diversity than that reported in the literature.
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