Homothiacalix[4]arenes: Synthetic Exploration and Solid-State Structures

Homothiacalix[n]arenes have been largely underexposed compared with related (homo)heteracalixarenes, although their inherent structural features are particularly attractive for supramolecular host-guest chemistry. In this contribution, the synthetic macrocyclization protocols that afford homothiacalix[n]arenes have been reinvestigated and optimized, providing straightforward access to the parent homothiacalix[4] arene skeleton. More-over, inner-rim (bis and tetrakis) ester functionalization and dimethylenethia bridge oxidation were successfully performed as well. Solution-phase (variable-temperature) NMR spectroscopy studies and solid-state X-ray structures provided complementary information on the conformational features of the novel macrocycles.