13C nuclear magnetic resonance spectral and conformational analysis of naturally occurring tetrahydrofuran lignans

Abstract

The ¹³C nmr spectra of the naturally occurring stereoisomers of the tetrahydrofuran lignans were recorded and the signals assigned. Based on these assignments, on the observed sensitivity of the benzylic carbon shifts to the orientation of the aryl groups, and on the comparison with previously reported ¹H nmr data, the most probable conformations for the mentioned stereoisomers are suggested.