Natural Products from the Hepaticae

This thesis consists of eight chapters, the first of which is a General Introduction dealing with the nature of secondary metabolites and the terpenoid and aromatic constituents of the Hepaticae (liverworts). This is followed by a discussion of the results of investigations into the chemical constituents of Herbertus aduncus and H. borealis (Chapter 2). From the former species six herbertane sesquiterpenoids were isolated (two of which are new natural products) and the structures determined mainly using 1H and 13C NMR spectroscopy. Studies of the fatty acid components of the triglycerides and cycloartenol esters of the species are also discussed. The chemical constituents of H. aduncus collected from four different sites and one collection of H. borealis are compared using 1H NMR and GLC techniques. Chapter 3 deals with the constituents of Anastrophyllum donnianum. Six new sphenolobane diterpenoids were isolated and their structures determined by spectroscopic methods. The constituents of this species, collected from three different sites, are contrasted using GLC and GCMS procedures. The structure of a bicyclogermacrane sesquiterpenoid is also discussed. The metabolites of Porella platyphylla form the subject matter of Chapter 4. Seven methoxylated pinguisanes and a new sacculatane diterpenoid were isolated from one sample of this species while another sample yielded two new pinguisanes. Their strugtures were assigned using 1H and 13C NMR spectroscopy. Chapter 5 describes the structural elucidation of nine new ent-kaurane diterpenoids and two new gymnomitrane derivatives from Jungermannia truncata. Three known ent-kauranes, a pimarane and a halimane were also isolated. The major part of Chapter 6 is concerned with the structural determination of a cadinane endoperoxide from Bazzania tricrenata using spectroscopic methods which included highfield (600 MHz) 1H and phase-sensitive DQF-COSY experiments. The calamenane sesquiterpenoid constituents of this liverwort are also discussed. The next chapter (Chapter 7) contains a discussion of the structural elucidation of a spirovetivane sesquiterpenoid from Lepidozia reptans. The final chapter (Chapter 8) describes the structural elucidation of two monoterpene hydroperoxides from Jungermannia obovata. The monoterpene and sesquiterpene hydrocarbon constituents of this liverwort are also discussed