1′,8.3′- and 7.3′,8.5′-Connected Bicyclo3.2.1octanoids and Oxabicyclo3.2.2nonane-Type Neolignans from Ocotea aciphylla: Structures and Absolute Configurations

The phytochemical investigation of the leaves and trunk bark of a specimen of Ocotea aciphylla collected in the southern portion of the Amazon forest led to the isolation of an oxabicyclo3.2.2nonane-type neolignan and 15 bicyclo3.2.1octanoid neolignans, 14 of which are unreported compounds (2–15), including one with an unusual oxidation pattern of the side chain at C-1′ and two rare 7.1′,8.3′-connected bicyclo3.2.1octanoid derivatives. Their structures and relative configurations were determined by extensive spectrometric analysis based on 1D- and 2D-NMR spectroscopy and HRESIMS data, while their absolute configurations were unambiguously assigned using electronic and vibrational circular dichroism data assisted by density functional theory calculations. Additionally, known sesquiterpenes, phenylpropanoids, and phytosterols were also isolated.