Conformational Analysis of trans ‐2,11‐Dithia‐4e,5,6,7e,8,9‐hexahydro[3.3]paracyclophane Using VT‐NMR

The conformation of trans ‐2,11‐dithia‐4 e ,5,6,7 e ,8,9‐hexahydro[3.3]paracyclophanes ( 5 , t DTHHPCP) was investigated by using 1 H NMR analysis under variable‐temperature condition. Based on the dynamic 1 H NMR behavior along with a structure obtained from simulation using the MM2 method, it has been deduced that 5 occurs preferentially in conformer 5a in CD 2 Cl 2 solution, which the two sulfur atoms are situated as the chair form and cyclohexano unit as a distorted boat form. The energy barrier (ΔG‡) for the inversion of the bridge (‐CH 2 SCH 2 ‐) has been estimated to be 11.6 kcal mol ‐1 (600 MHz, Tc = ‐30 °C). The proton chemical shifts are assigned for the individual hydrogen according to the spectra obtained at ‐70 °C.