trans-Cycloalkenes. Part 7. Variable temperature 13C nuclear magnetic resonance studies on cis,trans-cyclo-octa-1,5-diene and related compounds

Abstract

cis,trans-Cyclo-octa-1,5-diene (1) and the derived trans-bicyclo[6.1.0]non-4-ene (3) and its 9-oxa-(2) and 9-phenyl-9-aza-(3) analogues show temperature-dependent ¹³C n.m.r. spectra which are interpreted in terms of a conformational ring inversion process. The energy barriers for this process for compounds (1)–(4) are estimated to be 35, 41.5, 45, and 44.5 kJ mol^–1, respectively.