Stereoselective Intramolecular Enone-Olefin Photocycloadditions of 1,7-Dienes: Model Studies on the Synthesis of Lycopodium Alkaloids
نویسنده
چکیده
Paniculatine 1, magnellanine 2. and magnellaninone 3 are three structurally similar tetracyclic alkaloids isolated and characterized by Castillo in 1976.3 Despite their unusual and interesting structures, there has been a paucity of effort directed toward the synthesis of this class of alkaloids.3 We report hem our studies on the synthesis and characterization of two tricyclic intermediates which could development of a synthetic approach to several of these alkaloids.
منابع مشابه
Polycyclic Molecules from Linear Precursors: Stereoselective Synthesis of Clavolonine and Related Complex StructuresFinancial support was provided by the National Institutes of Health (GM 33328-20), Eli Lilly, Merck, and Amgen
At the time of this publication, over 100 lycopodium alkaloids have been isolated. The 16-carbon-atom-containing lycopodium alkaloid family features a variety of polycyclic ring sizes, stereochemistry, and oxidation patterns. The classic tetracyclic skeleton of the lycopodane family has a rich history in organic chemistry and has been a proving ground for new approaches to the synthesis of poly...
متن کاملIntramolecular Cyclization Strategies Toward the Synthesis of Zoanthamine Alkaloids.
Stabilized 2-amino-1,3-dienes can participate in intramolecular Diels-Alder (IMDA) reactions with pendant dienophiles. We found that these dienes can be readily prepared via standard palladium-mediated coupling reactions and have comparable reactivity to 2-oxodienes. Application of these substrates to the synthesis of tetracyclic model systems representing the ABCE motif of the zoanthamines is ...
متن کاملTotal synthesis of (+)-nankakurines A and B and (±)-5-epi-nankakurine A.
The first total syntheses of the Lycopodium alkaloids (+)-nankakurine A (2), (+)-nankakurine B (3), and the originally purported structure 1 of nankakurine A were accomplished. The syntheses of 2 and 3 feature a demanding intramolecular azomethine imine cycloaddition as the key step for generating the octahydro-3,5-ethanoquinoline moiety and installing the correct relative configuration at the ...
متن کاملSynthetic studies on bioactive natural polyketides: intramolecular nitrile oxide-olefin cycloaddition approach for construction of a macrolactone skeleton of macrosphelide B.
Studies on the synthesis of macrosphelide B via an intramolecular nitrile oxide-olefin cycloaddition (INOC) is described. In particular, an asymmetric INOC approach using phase transfer catalysts seems to be a potentially efficient and versatile procedure for the construction of the macrolactone skeleton of macrosphelide B in terms of facial selectivity. Our preliminary and unprecedented stereo...
متن کاملIsolation and complete structural assignment of Lycopodium alkaloid cernupalhine A: theoretical prediction and total synthesis validation.
Cernupalhine A (1) is a trace Lycopodium alkaloid (0.7 mg) possessing a new C17N skeleton with an unusual hydroxydihydrofuranone motif newly isolated from Palhinhaea cernua L. Its complete structural assignment, including absolute stereochemistry, was established through a combination of high-field NMR techniques and computational methods and further unequivocal confirmation by the first asymme...
متن کامل