Part I. Alkaloidal constituents of selected fractions of Thalictrum angustifolium L. and Thalictrum wangii Boivin (Ranunculaceae). Part II. A revision of the structure of thalprzewalskiinone. The synthesis of 2-methyl-6,7-dimethoxy-3'-methoxy-4'-hydro

Part I. Two plants were investigated in this study, Thalictrum angustifolium L. (Ranunculaceae) and Thalictrum wangii Boivin. The former plant was supplied by Professor. Raymond W. Doskotch of the Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, while the latter plant was obtained from Dr. Gao-Yuan, Professor adjuster of National Ranks on Metrology Accreditation, Standing Chairman of Analysis and Computation Center, Director of NMR Lab and Department of Spectral Analysis, Beijing Medical University. Thalictrum, a genus of plants within the family Ranunculaceae, is distributed throughout the world but is centered in temperate and cold regions of the Northern and Southern Hemisphere. The goal of this study was to isolate and identify novel alkaloids that had not been previously found in nature, and to expand the chemotaxonomic knowledge associated with the genus Thalictrum and the family Ranunculaceae.; The introduction consists of a review of some classes of alkaloids that were represented by the alkaloids isolated from the two investigated species. The experimental section provides detailed information about the materials and methods used in isolation and structure elucidation of the following compounds: berberine iodide (13), magnoflorine iodide (1), jatrorrhizine iodide (55), methyl-4-hydroxybenzoate (57 ), noroxyhydrastinine (58), and Omethylthalicberine ( 59) from Thalictrum angustifolium; and berberine iodide (13), magnoflorine iodide (1), thalmelatidine ( 60), and thalibealine (61) from Thalictrum wangii . Thalibealine (61) is a novel alkaloid that represents the first member of the aporphine-tetrahydroprotoberberine dimeric class. This part of the dissertation concludes with a discussion of the important spectral data (particularly the one and two-dimensional magnetic resonance spectra and mass spectra) that were utilized in the identification of the isolates described above.; Part II. A new oxobenzylisoquinoline alkaloid, thalprzewalskiinone, was isolated from the roots of Thalictrum przewalskii Maxim in 1999. The structure of this new alkaloid was assigned as 2-methyl-6,7-dimethoxy-3′-methoxy-4 ′-hydroxyoxobenzylisoquinoline (147) based on a consideration of the available spectral data. The goal of this investigation was the total synthesis of 2-methyl-6,7-dimethoxy-3′methoxy-4 ′-hydroxy-oxobenzylisoquinoline (147) and its positional isomer 2-methyl-6,7dimethoxy-3′-hydroxy-4′ -methoxy-oxobenzylisoquinoline (154) in order to unambiguously confirm or refute the original structural assignment. The introduction consists of a review of both the oxobenzylisoquinoline alkaloids that have been isolated from the genus Thalictrum, and the current literature methods utilized in the synthesis of benzylisoquinolines. The experimental section focuses on the total synthesis of 2-methyl-6,7-dimethoxy-3′-methoxy-4 ′-hydroxy-oxobenzylisoquinoline (147) and 2-methyl-6,7-dimethoxy-3 ′-hydroxy-4′-methoxy-oxobenzylisoquinoline (154), using the appropriate Reissert compound.; The discussion presents a direct comparison of the spectral data (particularly the ultraviolet and magnetic resonance spectra) of synthetic 2-methyl-6,7-dimethoxy-3 ′-hydroxy-4′-methoxyoxobenzylisoquinoline iodide (154) and synthetic 2-methyl-6,7 dimethoxy-3′ -methoxy-4