Synthetic strategy previous studies

A second synthetic study in this area by Corey culminated in the synthesis of erythronolide A (146) as outlined in Scheme 2.15. The strategy employed in this synthesis was quite similar to that utilized for erythronolide B save two important points. Quite obviously, the additional hydroxyl group at C-12 requires a somewhat different route to the C-10 to C-13 fragment. Second, the presence of the C-12 hydroxyl group resulted in significantly more protecting-group manipulations relative to the sequence employed in the previous synthesis. 

In conclusion, by overcoming the disadvantage of the previous synthetic methods for the preparation of hyperbranched polymers, we designed an all-new Seesaw-type macromonomer strategy to construct perfect hyperbranched model samples with uniform subchains. In onr stndy, we successfully prepared various kinds of Seesaw-type macromonomers, snch as homopolymers, triblock copolymers and diblock copolymers. Using these maCTomonomers as precursors, we have further prepared a series of perfect hyperbranched homopolymers, block copolymers, graft copolymers and hetero-snbchain copolymers by a combination of controlled/ living polymerization and click chemistry. Various solution properties of these novel hyperbranched (co) polymers in dilnte and semidilute solntions have been studied in detail. More specifically, the main achievements of this work are as follows ... 

During this period, its structure was established by its total syntheses and its biological activity was well-studied. Die total synfliesis of lyso gic acid (1) has attracted the significant attention of synthetic organic chemists, as wimessed by the number of total syntheses so far achieved, which now count to nine. All of these tyipeared in a short span of time in the nineties, except for the first one by Woodward and Komfeld. Only one new addition to the list appeared since the previous review written in 1990 (J), where all the syntheses were well-documented, showing that the research in this decade has been focused in other directions. Here the authors want to mention briefly the total syntheses previously carried out simply for the basic strategies involved. 

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