Abstract
The one-pot coupling reactions of bis (2-isocyano-2-tosylethyl) benzenes (5) with phthalaldehydes (11) afforded dioxazolo [32] cyclophanes (12a, 12d, 12e, 12f, and 12h), bis (naphth [2, 1-d] -oxazol-4-yl) benzenes (13a-c), and tetraoxazolo [34] parametacyclophane (14) as 1 : 1, 1 : 2, and 2 : 2 adducts, respectively. On the basis of the variable-temperature nuclear magnetic resonance (VT-NMR) spectra of dioxazolo [32] metacyclophane (12e), 12e in solution at room temperature exists in a syn form and the energy barrier to the conformational change (ΔG_??_) at the coalescence temperature (Tc = 38 °C) is determined to be 64.5 kJ/mol, which is higher than that of parent [32] metacyclophane (1). Therefore, it was suggested that the annelations of two oxazole rings to the two methylene bridges of 1 significantly affected the mobility of the benzene rings of 12e.
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