magellanine and magellaninone

(-)-Magellanine, (+)-magellaninone, and (+)-paniculatine are three natural products isolated from the

Topics: Acetylcholinesterase; Alkaloids; Biological Products; Lycopodium; Molecular Structure

A unified route for the total synthesis of three tetracyclic diquinane

Topics: Alkaloids; Heterocyclic Compounds, 4 or More Rings; Lycopodium; Molecular Structure; Stereoisomerism

Starting from inexpensive (+)-pulegone as the chiral building block, a highly convergent synthesis of the unusual diquinane-based structures of (+)-paniculatine (1), (-)-magellanine (2), and (+)-magellaninone (3), has been achieved. This approach is based upon a tandem acylation-alkylation of ketoester 8 and palladium-catalyzed olefin insertion, oxidation, and hydrogenation for construction of the tetracyclic framework. This exceedingly concise strategy, requiring only 12-14 steps, is the shortest to date.

Topics: Alkaloids; Alkenes; Alkylation; Catalysis; Heterocyclic Compounds, 4 or More Rings; Hydrogenation; Lycopodium; Molecular Structure; Palladium; Stereoisomerism

The collective total synthesis of tetracyclic diquinane Lycopodium alkaloids, (+)-paniculatine, (-)-magellanine, (+)-magellaninone, and two analogues (-)-13-epi-paniculatine and (+)-3-hydroxyl-13-dehydro-paniculatine, has been accomplished. By logic-guided addition of a strategically useful hydroxyl group at C-3 of paniculatine, the formidable tetracyclic core was rapidly synthesized utilizing a site-specific and stereoselective aldol cyclization, thus making the ABD → ABCD tetracyclic approach to diquinane Lycopodium alkaloids attainable for the first time.

Topics: Alkaloids; Cyclization; Heterocyclic Compounds, 4 or More Rings; Lycopodium; Molecular Structure

The total syntheses of (-)-magellanine, (+)-magellaninone, and (+)-paniculatine were completed from diethyl l-tartrate via the common intermediate in a stereoselective manner. The crucial steps in these syntheses involved two intramolecular Pauson-Khand reactions of enynes: the first Pauson-Khand reaction constructed the bicyclo[4.3.0] carbon framework, the corresponding A and B rings of these alkaloids in a highly stereoselective manner, whereas the second Pauson-Khand reaction stereoselectively produced the bicyclo[3.3.0]skeleton, which could be converted into the C and D rings of the target natural products.

Topics: Heterocyclic Compounds, 4 or More Rings; Lycopodium; Molecular Conformation; Stereoisomerism