Photochemical reactions contribute in a significant way to the existing repertoire of carbon-carbon bond-forming reactions by allowing access to exceptional molecular structures that cannot be obtained by conventional means. In this Review, the most important photochemical transformations that have been employed in natural product synthesis are presented. Selected total syntheses are discussed as examples, with particular attention given to the photochemical key step and its stereoselectivity. The structural relationship between the photochemically generated molecule and the natural product is shown, and, where necessary, the consecutive reactions in the synthesis are illustrated and classified.

Photochemical reactions as key steps in natural product synthesis

Marihuana Chemistry: Recent advances in cannabinoid chemistry open the area to more sophisticated biological research.

Natural products have been a rich source of agents of value in medicine. They have also inspired, at various levels, the fashioning of nonnatural agents of pharmaceutical import. Hitherto, these nonnatural derivatives have been primarily synthesized by manipulating the natural product. As a consequence of major innovations in the subscience of synthetic methodology, the capacity of synthesis to deal with molecules of considerable complexity has increased dramatically. In this paper, we show by example some total syntheses which draw from strategy-enabling advances in methodology. Moreover, we show how these capabilities can be used to discover and develop new agents of potential pharmaceutical value without recourse to the natural product itself.

Small molecule natural products in the discovery of therapeutic agents: the synthesis connection.

In 1996, the US Environmental Protection Agency was given a mandate by Congress to develop a screening program that would evaluate whether variously identified compounds could affect human health by mimicking or interfering with normal endocrine regulatory functions. Toward this end, the Agency chartered the Endocrine Disruptor Screening and Testing Advisory Committee in October of that year that would serve to recommend a series of in vitro and in vivo protocols designed to provide a comprehensive assessment of a chemical's potential endocrine-disrupting activity. A number of these protocols have undergone subsequent modification by EPA, and this review focuses specifically on the revised in vivo screening procedure recommended under the title Research Protocol for Assessment of Pubertal Development and Thyroid Function in Juvenile Female Rats. Background literature has been provided that summarizes what is currently known about pubertal development in the female rat and the influence of various forms of pharmaceutical and toxicological insult on this process and on thyroid activity. Finally, a section is included that discusses technical issues that should be considered if the specified pubertal endpoints are to be measured and successfully evaluated.

Endocrine-disrupting chemicals: prepubertal exposures and effects on sexual maturation and thyroid activity in the female rat. A focus on the EDSTAC recommendations

AnnulationS, derived from the Latin work annulatus (ringed) means “the formation of rings”.’ In organic chemistry this term is used to describe the process of building a ring onto a preexisting system. cyclic or non-cyclic. The added ring may be of any size, although 5and ~membered rings are most commonly formed. This broad de~nition includes in a general sense many reactions that are not normally thought of as annulation reactions, such as Diels-Alder reactions.’ acid-catalyzed polyolefinic cyclizations,’ photochemical,’ radical,‘ and thermal’ cyclizations. This discussion will be concerned mainly with those processes of annulation which involve construction of a cyclohexenone ring onto a me-existing ketone; e.g. 1 -+t. These processes normally involve the

A Review of Annulation

975. Totally synthetic steroid hormones. Part I. Oestrone and related œstrapolyenes

Biological effects of racemic and resolved 13β-ethyl-4-gonen-3-ones

856. Totally synthetic steroid hormones. Part II. 13β-Alkylgona-1,3,5(10)-trienes, 13β-alkygon-4-en-3-ones, and related compounds

Biological Effects of Synthetic Gonanes

Totally synthetic steroid hormones. 13. The chemical resolution of some racemic estrane, 13-beta-ethylgonane, and 13-beta-n-propylgonane derivatives and the preparation of some estrane and 13-beta-ethylgonane derivatives of unnatural configuration.

Hughes Gordon A

Papers

975. Totally synthetic steroid hormones. Part I. Oestrone and related œstrapolyenes

Biological effects of racemic and resolved 13β-ethyl-4-gonen-3-ones

856. Totally synthetic steroid hormones. Part II. 13β-Alkylgona-1,3,5(10)-trienes, 13β-alkygon-4-en-3-ones, and related compounds

Biological Effects of Synthetic Gonanes

Totally synthetic steroid hormones. 13. The chemical resolution of some racemic estrane, 13-beta-ethylgonane, and 13-beta-n-propylgonane derivatives and the preparation of some estrane and 13-beta-ethylgonane derivatives of unnatural configuration.