Configurational Assignments of Conformationally Restricted Bis-Monoterpene Hydroquinones: Utility in Exploration of Endangered Plants

Abstract

Endangered plant species are a prominent resource for new chemistry. Lindera melissifolia is native to the Southeastern U.S. and scarcely populates the edges of lakes and ponds. Two meroterpenoids, melissifolianes A (1) and B (2) were purified and the 2-D structures elucidated using NMR and HRESIMS. The relative configuration of 1 was established employing the combination of NOE-based distance restraints and the comparisons of experimental and calculated coupling constants. The comparison of calculated and experimental ECD established the absolute configuration of 1. The relative configuration of a racemic mixture, melissifoliane B (2) was assigned utilizing J-based analysis combined with quantum mechanics and NMR techniques.