Connection of isolated stereoclusters by combining 13C-RCSA, RDC, and J-based configurational analyses and structural revision of a tetraprenyltoluquinol chromane meroterpenoid from Sargassum muticum

The seaweed Sargassum muticum, collected on the southern coast of Galicia, yielded a tetraprenyltoluquinol chromane meroditerpene compound known as 1b, whose structure is revised. The relative configuration of 1b was determined by J-based configurational methodology combined with an iJ/DP4 statistical analysis and further confirmed by measuring two anisotropic properties: carbon residual chemical shift anisotropies (13C-RCSAs) and one-bond 1H-13C residual dipolar couplings (1DCH-RDCs). The absolute configuration of 1b was deduced by ECD/OR/TD-DFT methods and established as 3R,7S,11R.Agencia Estatal de Investigación (AEI) de España | Ref. RTI2018-093634-B-C22Interreg España-Portugal | Ref. 0474_BLUEBIOLAB_1_EXunta de Galicia | Ref. GRC2018/039Xunta de Galicia | Ref. ED431E 2018/03Max Planck Society | Ref. CAPES 418729698SERB, New Delhi | Ref. ECR/2017/00181