Conformational interconversions of partially dehydroxylated calix[4]arenes. A molecular mechanics study

The rotational pathways of the cone double left right arrow cone topomerisa tion for a series of dehydroxylated calix[4]arenes 2-5 have been calculated using the MM3 force field. The key intermediates and rate-limiting steps h ave been identified and characterised. The low barriers obtained for phenyl residue rotation suggest that the compounds should be partially flexible a t low temperatures. The results are discussed in relation to available expe rimental data.