Conformational behaviour of medium-sized rings. Part 9. Disalicylides and trisalicylides

Total Synthesis of the Proposed Structure of Ardimerin, and Proposal for its Structural Revision

“…In the 1 H‐NMR spectra of 28 ((D 6 )DMSO, 400 MHz), the geminal coupling between two Bn H‐atoms was observed, suggesting the eight‐membered salicylide core possesses bowl chirality. [7] To observe the dynamic behavior, variable‐temperature 1 H‐NMR experiments were performed. During raising the temperature, the peaks became broadened and coalesced at 355 K, and further heating sharpened the peak.…”

“… b ), the medium‐sized ring imposes the unfavorable s‐cis conformation. [7] Thus, construction of such eight‐membered salicylides is challenging, and reported approaches have been limited, e.g ., condensation of salicylic acid derivative[8] and the Baeyer–Villiger oxidation of cyclohexanedione. [7a] Indeed, Minehan et al .…”

The dynamic chromatographic behavior of tri-o-thymotide on HPLC chiral stationary phases

“…However, the same helix to helix process in two trilactones closely related to TOT was investigated by D-NMR and gave energy barriers of 14.3 AE 0.5 kcal mol À1 for tris-3,6-dimethylsalicylide and 17.6 AE 0.2 kcal mol À1 for tri-o-carvacrotide, suggesting a much faster process compared to the propeller to helix exchange. 2 In the solid state, neat TOT as well as TOT complexed with guests are always found in a flattened three-bladed propeller conformation with approximate C 3 symmetry. 1c Interest in the TOT molecule and in its complexation behavior is due to the ability of TOT to give spontaneous resolution when forming clathrate inclusion crystals with a large variety of guests.…”