Target preparation construction strategies

There has been a significant level of activity in the synthetic arena directed toward the preparation of lycorine and related alkaloids, and a number of successes have been recorded. Although a variety of strategies for the elaboration of the tetracyclic skeleton of lycorine have evolved, the most common ones, and those that have ultimately led to the total syntheses of the target alkaloids, are of the general type A — C —> B - D and A— C D B. Of some importance is an approach which involves prior construction of the C and D rings followed by the elaboration of the A and B rings. At this juncture, it is appropriate to note... 

The target Cu(l)-complexed [2]catenane contains two different macrocycles. Therefore, two routes can be envisaged for its construction by the transition metal templated strategy [64]. They are shown in Fig. 17. Both involve the preparation of an intermediate precatenane species, (C) or (F), in which either Zn or Au porphyrin-containing macrocycle (A) or (E) is threaded onto chelate (B), thanks to copper(I) coordination. Formation of the second, inter-... 

In this chapter, the chemistry of sialic acid is briefly reviewed and some advantages and problems of strategies described for the construction of the a-ketosidic linkage of sialic acid and complicated sialosides are presented. Experimental details are also provided to allow practical preparation of the chosen targets. 

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