The Humulinic Acids III. The NMR Spectra and the Structure of HAA and HAB

Abstract

Abstract A detailed analysis of the proton magnetic resonance (PMR) spectra of humulinic acid A and humulinic B shows that the former is the trans and the the latter the cis form with structures I and II respectively. Evidence is advanced that J trans is smaller than J cis in ring compounds with several sp 2 carbon atoms in the ring.