Plants of the family Guttiferae produce polycyclic polyprenylated acylphloroglucinols (PPAPs), which have interesting biological activities including anticancer and antibacterial properties. The main structural features of PPAPs comprise of bicyclo[3.3.1]nonane-2,4,9-triketone with one acyl group together with prenyl, geranyl, or other C10H17 groups. 7-epi-Clusianone, a type B PPAP with C-7 endo stereochemistry, is being approached by establishing the cis relationship with C(4) allyl group and C(2) methyl ester in the early stage of the synthesis. Then C(2) methyl ester is converted to alkyne aldehyde and syn reduction followed by intramolecular aldol reaction to give bicyclo[3.3.1]nonane structure with C(7) endo stereo chemistry.

Polycyclic Polyprenylated Acylphloroglucinols (PPAPs) are a vast family of natural products, which includes more than 200 members. They contain a stunningly complex molecular architecture which in most cases includes a bicyclo[3.3.1]nonane core. PPAPs have been of interest to the scientific community for their intricate structure, their powerful aid in treating many ailments and large portfolio of biological activities. More particularly, they have been of synthetic interest since 1999 with the first report of an approach to these complicated cores by Nicolaou. Herein, we present the first total synthesis of papuaforin A, papuaforin B, papuaforin C, hyperforin and the formal synthesis of nemorosone following a report by Simpkins and co-workers. We relied on a gold(I)-catalyzed carbocyclization for the construction of the core of this family of natural products. Ginkgolides are isolated from the ginko tree, Ginkgo biloba, a living fossil with records of its existence dating back 280 million years. For centuries, the plant and its extracts have been used extensively for their beneficial properties, especially in China, Japan and India. For example, extract Egb761, one of the most potent fraction, generates over $500 million a year alone. The ginkgolides possess a truly unique compact diterpene framework of six 5-membered rings with a high content oxygen. Eleven oxygens can be found in ginkgolide C for a core containing only 23 carbons. The ginkgolides also include a very unique feature: a tert-butyl group located on the most convoluted ring system: the B ring. Few groups have found success in limning a synthetic route to ginkgolides. Corey’s group was the first to achieve the total synthesis of ginkgolide B in 1987. He was also able to complete ginkgolide A a year later. Crimmins and co-workers also achieved the total synthesis of ginkgolide B a decade later in 1999. Herein, we present our new approach toward ginkgolides through a newly developed methodology for the α-allylation of ketones and the creation of highly hindered contiguous quaternary centers. The synthesis is still at an early stage but a synthetic pathway giving access to the ring B with all the key moieties has been extensively investigated.

La guttiférone A , appartenant à la famille des PPAPs ou Acyle Phloroglucinol Polycycliques Polyprénylées, est une molécule extraite à partir d’un arbre tropicale, le Symphonia globulifera. Cette matière première est abondante et peut être facilement obtenue. De plus, elle présente de nombreuses activités biologiques, lui conférant un potentiel pharmacologique très intéressant. Trois approches ont été effectuées durant ces travaux. La première fût l’utilisation de microorganismes pour effectuer des biotransformations. L’utilisation de levures a permis de synthétiser la 3,16-oxy-guttiférone A, forme xanthone de la guttiférone. Le second axe a été d’utiliser des outils chimiques pour obtenir des dérivés de la guttiférone A. Dans un premier temps, une vingtaine d’analogues éther et ester du catéchol a été synthétisée, certains de ces composés ont montré un meilleur indice de sélectivité sur les parasites. Une synthèse sélective de xanthone par une réaction de couplage phénolique oxydatif a également été étudiée. Nous avons pu obtenir par cette approche la 3,16-oxy-guttiférone A, la 1,16-oxy-guttiférone A et la 1,12-oxy-guttiférone A. Ces réactions ont aussi donné accès à des dérivés xanthone hydroxylée jamais décrits dans la littérature. Enfin, un travail préliminaire de phytochimie sur les graines et feuilles du Symphonia globulifera a été réalisé, permettant d’isoler des analogues de la guttiférone A, la guttiférone C et D, ainsi que d’autres molécules comme des bisflavonoides et des xanthones. / Guttiferone A, belonging to the PPAPs family (Polycyclic Polyprenylated Acylphloroglucinols), is extracted from a tropical tree called Symphonia globulifera. This raw material is abundant and can be easily obtained. In addition, it has many biological activities, giving it a very interesting pharmacological potential. Three approaches were used in this work. The first was the use of microorganisms to perform biotransformations. The use of yeast allow the synthesis of 3,16-oxy-guttiférone A, a xanthone derivative of guttiferone A. The second theme was the use of chemical tools for guttiferone A derivation. First, twenty ether and ester catechol analogs were synthesized, some of these compounds showed a better selectivity index of parasites. Selective synthesis of xanthone by phenolic oxidative coupling reaction was also studied. We obtained by this approach the 3.16-oxy-guttiferone A, 1,16-oxy-guttiferone A and 1,12-oxy-guttiferone A. These reactions have also provided some hydroxylated xanthone never described before in the literature. Finally, preliminary phytochemical work on seeds and leaves of Symphonia globulifera lead to the isolation of guttiférone A analogues such as guttiférone C and D, as well as other molecules such as bisflavonoides and xanthones.