The Conformations of 1-Thiacyclooctan-3-One Dynamic Nuclear Magnetic Resonance and Force-Field Calculation

Abstract

<em>The ¹H and natural-abundance ¹³C-NMR spectra of 1-thiacyclooctan-3-one (1) have been measured from 25 to -100°C. Coalescence is observed in the ¹H-NMR spectra of (1) at about -80°C, and attributed to ring inversion in a boat-chair conformation, which is the predominant conformation of (1). The free energy of activation (</em><em>D</em><em>G</em><em>^¹</em><em>) for this process is 9.2</em><em>±</em><em>0.2 kcal/mol. The ¹³C-NMR spectra of (1) is temperature independent.</em>