Ultrastructural observations reveal that the spermatozoid of Lycopodium obscurum is crescent shaped and contains two posteriorly directed flagella that are inserted at the front of the cell. The nucleus is broad and elongated with a narrow posterior projection or nuclear diverticulum. Spline microtubules (MTs) number 180 at their maximum and provide the framework for the cell. These MTs extend from the anterior of the locomotory apparatus and along the outermost surface of the nucleus, with a central shank of 14-17 MTs encircling the cell for at least one-third gyre beyond the nucleus. The two basal bodies are slightly staggered and positioned at the front of the cell over a highly elongated multilayered structure (MLS). The MLS extends laterally around the cell anterior and curves posteriorly over the nucleus. One large anterior mitochondrion is situated subjacent to the MLS, while numerous small mitochondria are scattered near or among the lobes of the single plastid. The plastid rests on the inner nuclear surface and contains numerous large starch grains. This cell differs from that of L. cernuum, the only other species of Lycopodium examined to date, in that it is more elongated and has an anterior-posterior orientation of the nucleus, basal bodies, MLS, and spline. Comparisons with coiled gametes of bryophytes and Selaginella suggest that some degree of coiling and cell streamlining may be ancestral in archegoniate spermatozoids.

Yes / The photoprotection and isolation of marinomycin A using sporopollenin exine capsules (SpECs) derived from the spores of the plant Lycopodium clavatum is described. The marinomycins have a particularly short half-life in natural light, which severely impacts their potential biological utility given that they display potent antibiotic and anticancer activity. The SpEC encapsulation of the marinomycin A dramatically increases the half-life of the polyene macrodiolide to the direct exposure to UV radiation by several orders of magnitude, thereby making this a potentially useful strategy for other light sensitive bioactive agents. In addition, we report that the SpECs can also be used to selectively extract culture broths that contain the marinomycins, which provides a significantly higher recovery than with conventional XAD resins and provides concomitant photoprotection.

<p> An investigation of flabelliformine, an alkaloid obtained from Lycopodium flabelliforme, led to the establishment of its structure. </p> <p> A study of the mass spectra of annotine (a minor alkaloid present in Lycopodium annotinum) and several of its derivatives in combination with degradative work gave support to a total structure proposed previously for the alkaloid.</p> <p> A synthetic approach to the Lycopodium alkaloids was considered. 1-Carbomethoxy-3-methyl-7-methoxybicyclo [3.3.1] non-3-en-9-one, a compound which appeared suitable as an intermediate in the synthesis, was prepared in low yield. The difficulty encountered in the purification of this compound, coupled with the low yield in which it was obtained, indicated the impracticality of this approach to a total synthesis of a Lycopodium alkaloid.</p> / Thesis / Doctor of Philosophy (PhD)

<p> The biosynthesis of lycopodine was studied by feeding radioactive acetate, acetoacetato, lysine and pelletierine to Lycopodium tristachyum. Partial degration of the radioactive lycopodine recovered from these experiments revealed specific incorporation of these precursors. The labeling pattern obtained is discussed in the light of the two major blogenetic hypothesis advanced for the Lycopodium alkaloids. </p> <p> The results obtained disproved Conroy's polyacetate hypothesis. They are consistent with the hypothesis that regards these alkaloids derived from lysine and acetate. </p> / Thesis / Doctor of Philosophy (PhD)

Part (i) -The Minor Alkaloids: Annotoxine, C32H44O5N2, has now been isolated from a Canadian source. It has been separated into the alkaloids acrifoline, C16H23O2N, and annotine (alkaloid L 11), C16H21O3N. Both alkaloids have been shown to possess one hydroxyl group, one carbonyl group and one centre of unsaturation. The lack of reactivity of the third oxygen function of annotine suggests that it is present in an ether linkage. The identity of O-acetylacrifoline with alkaloid L 12 has also been proved. Part (ii) -Diphenylannotinine: Diphenylannotinine has been shown to be C28H33O3N. It possesses two hydroxyl groups, the third oxygen is present in an ether linkage. The exact nature of the ether linkage could not be ascertained on the basis of the experimental evidence. / Thesis / Master of Science (MSc)

Lomaiviticin A (1) and B (2) are natural products with remarkably complex C2-symmetric structures and potent antiproliferative properties. Achieving total syntheses of 1 and 2 has been a long-standing project in the Shair group and part one of this thesis describes our first successful synthesis of the C4-epi-lomaiviticin A and B core structures. A key stereoselective oxidative enolate dimerization of an oxanorbornanone system was employed to establish the highly hindered C2-C2' bond. Crucial to our completion of the lomaiviticin core structures was the discovery of subtle yet far-reaching stereoelectronic effects imparted by the C4/C4'-stereocenters. The Lycopodium alkaloids are a family of complex polycyclic alkaloid natural products that have long served as popular targets for developing synthetic chemistry. More recently, select members have been reported to exhibit neurological effects. Part two of this thesis presents the development of a biomimetic, unified strategy for the synthesis of 7-membered ring-containing Lycopodium alkaloids and its successful application toward the first total syntheses of the proposed structure of (-)-himeradine A (38), (-)-lycopecurine (39), and (-)-dehydrolycopecurine (199), and the syntheses of (+)-lyconadin A (31) and (-)-lyconadin B (32). A biosynthetically inspired one-pot cascade reaction sequence was developed to construct the strained polycyclic core structure shared amongst these alkaloids. Additionally, the syntheses of 38, 39, and 199 featured a biomimetic intramolecular Mannich reaction to furnish the tetracyclic ring system. The successful application of our unifying strategy toward the synthesis of a diverse set of alkaloids lends support to our biosynthetic hypothesis that 7-membered ring-containing Lycopodium alkaloids arise from a common precursor. Our synthetic approach can potentially provide access to all such natural products. / Chemistry and Chemical Biology

No description available.

Gold catalysis has attracted much attention within the chemical community in recent years, and its importance as a synthetic tool has only started to be uncovered. This thesis describes the development of a gold(I) catalyzed transformation and its application to the synthesis of a structurally unique Lycopodium alkaloid, Magellanine. Although there have been a few reports on the synthesis of the magellanane core to date, the approach described herein would represent a new and efficient strategy to construct the angularly fused tetracyclic core. The 5 exo dig/Prins reaction that would be the key step of the synthesis was first developed and studied on a model substrate, enabling the verification of the hypothesis that this transformation could indeed form the A and B rings of Magellanine and be applied to its synthesis. This reaction formed the tricyclic products in good yields and in good exo:endo ratios. The synthesis of Magellanine was undertaken, but problems of isomerization prevented the synthesis of the desired 5 exo dig/Prins substrate, which contained the C and D rings of Magellanine with a cis relationship at the ring junction. However, an almost identical substrate, save for a trans configuration between the C and D rings instead of the cis configuration, was prepared and served in further establishing the applicability of this methodology to the synthesis of Magellanine by successfully undergoing the 5-exo-dig/Prins reaction and generating the tetracyclic products. Studies of the steps following the key transformation were performed on the model substrate, allowing for the evaluation of these steps prior to their use in the synthesis. The results of the studies indicate a possible need to revisit the order in which the steps should be carried out. Promising solutions to the different obstacle encountered during the work are presented, demonstrating how the synthesis of Magellanine through a route featuring the 5-exo-dig/Prins cyclization is attainable.

In this thesis is presented work carried out during the course of the last 42 months. It concerns approaches towards total syntheses of the complanadine alkaloids. The main focus is the development of a model system to establish the viability of the key step in our proposed route to the complanadines. The thesis is divided into five chapters. Chapter 1 is an introduction to the complanadines, their biological activity and accomplished total syntheses to date. A brief introduction to the Diels–Alder reaction and selected examples of its application in the total syntheses of natural products are given. The Kondrat’eva oxazole–olefin hetero-Diels–Alder reaction as a method of pyridine formation is described and its application in the total synthesis of natural products is reviewed. Chapter 2 is the first part of the results and discussion section. It details our retrosynthetic analysis of complanadine A, outlines the corresponding proposed forward synthesis and presents a model system designed and synthesised to test the applicability of the Kondrat’eva oxazole–olefin hetero-Diels–Alder reaction in the context of our proposed total synthesis. Chapter 3 discusses work carried out in approaches to the total synthesis of complanadines and their monomeric subunit, lycodine, by means of the methodology developed in the previous chapter. Chapter 4 is the experimental section, which gives descriptions of the synthetic procedures employed and spectroscopic data for all compounds synthesised, both novel and previously reported, as discussed in Chapter 2 and Chapter 3. Supplementary information such as X-Ray data for synthesised compounds and selected NMR spectra are enclosed in the appendices.

Gold catalysis has attracted much attention within the chemical community in recent years, and its importance as a synthetic tool has only started to be uncovered. This thesis describes the development of a gold(I) catalyzed transformation and its application to the synthesis of a structurally unique Lycopodium alkaloid, Magellanine. Although there have been a few reports on the synthesis of the magellanane core to date, the approach described herein would represent a new and efficient strategy to construct the angularly fused tetracyclic core. The 5 exo dig/Prins reaction that would be the key step of the synthesis was first developed and studied on a model substrate, enabling the verification of the hypothesis that this transformation could indeed form the A and B rings of Magellanine and be applied to its synthesis. This reaction formed the tricyclic products in good yields and in good exo:endo ratios. The synthesis of Magellanine was undertaken, but problems of isomerization prevented the synthesis of the desired 5 exo dig/Prins substrate, which contained the C and D rings of Magellanine with a cis relationship at the ring junction. However, an almost identical substrate, save for a trans configuration between the C and D rings instead of the cis configuration, was prepared and served in further establishing the applicability of this methodology to the synthesis of Magellanine by successfully undergoing the 5-exo-dig/Prins reaction and generating the tetracyclic products. Studies of the steps following the key transformation were performed on the model substrate, allowing for the evaluation of these steps prior to their use in the synthesis. The results of the studies indicate a possible need to revisit the order in which the steps should be carried out. Promising solutions to the different obstacle encountered during the work are presented, demonstrating how the synthesis of Magellanine through a route featuring the 5-exo-dig/Prins cyclization is attainable.