Prospects for total synthesis

Prospects for Total Synthesis. At the present time, the prospects for the further development of total steroid synthesis are closely connected with the possibilities of its use in industry. To evaluate these 

The main problem of a multistage synthesis is the over-all yield, which decreases exponentially with an increase in the number of stages in accordance with the formula given below, where is the over-all yield, r is the yield in each stage, and n is the number of stages  

The selection of the synthetic routes is of primary importance for multistage syntheses. The number of theoretically possible variants is extremely large. Thus, if the synthesis consists in the addition of ten fragments in the course of nine reactions, the total number of possible variants exceeds 5000. The limitations imposed by the presence of centers of asymmetry and the nature of the functional substituents affect the sequence of building up of the fragments of the molecule and essentially restrict the number of synthetic schemes that can be realized in practice as compared with the numerous theoretically possible combinations. Nevertheless, at the present time the selection of the synthetic route is more of an art than a science. 

Each of these routes has its advantages and disadvantages which must be taken into account in selecting the method of synthesis for concrete 

The production of steroid hormones from natural steroids by partial synthesis has recently achieved a high degree of perfection [23], Conse- 

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Keding SJ, Danishefsky SJ. Prospects for total synthesis a vision for a totally synthetic vaccine targeting epithelial mmors. Proc. Natl. Acad. Sci. U.S.A. 2004 101 11937-11942. 

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