High-level synthesis overview

Cydic systems usually adopt distinct preferred conformations, which frequently allow them to pass throu a single reactive conformation in the course of a chemical reaction this may result in the formation of a sin e product. In this contesl, addition of organocuprates to a number of chiral, cydic enone systems frequently occurs vtith high levels of stereoselectivity. Historically, this chemistry has had a major impact on the fidd of total synthesis of steroids and prosta andins [la, k]. In this chapter we would thus like to present an overview of the most general stereochemical trends underlying the addition of organocuprates to chiral cydic enones. 

In order to provide a clear overview of the work described in this book and the way in which the other chapters are linked, they will be listed below with a short description of their content. The intention in the chapters of this book has not been to describe the novel synthesis techniques in detail. Many results have already been published in conferences and journals which deal with these techniques. The most important publications are listed in the bibliographies of the individual chapters. Instead, most of the emphasis will be placed on the high-level methodologies and on how these are inspired by the targeted application domains. In addition, most results are illustrated with a realistic demonstrator application. This will permit easy assessment of the power and the impact of the obtained results. It will also clarify the current status of the realization of the synthesis tools and environments. 

The application of permeable composite monolith membranes for the FT synthesis has been tested [122]. An overview of concepts associated with this reactor type has been presented (Figure 12.25) [123]. Novel uses of this concept have been advanced, and some experimental results have demonstrated the ability to operate at high CO conversion with metal FT catalysts by removal of the water produced during the synthesis [ 124] and the encapsulation of an FT catalyst by a zeolite membrane layer to effect upgrading reactions in the FT reactor [125]. The potential of this technique merits further studies to evaluate the ability to scale to a commercial level. 

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