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

Abstract

The conformation of trans‐2,11‐dithia‐4e,5,6,7e,8,9‐hexahydro[3.3]paracyclophanes (5, tDTHHPCP) was investigated by using 1H NMR analysis under variable‐temperature condition. Based on the dynamic 1H 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 CD2Cl2 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 (‐CH2SCH2‐) 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.

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