Problem of Complex Targets

The targets analyzed to this point have been structurally and stereochemically simple. When complex targets are chosen, the ability to synthetically reconnect the bond that is disconnected is not the only criterion 

The second key step is lactone formation from the carboethoxy substituted cyclohexanone unit in 44. The third key step is construction of the tricyclic ring system by asymmetric radical cyclization of 43, and construction of 43 from 2-isopropylphenol (42) using alcohol chiral auxiliaries (R OH) was designated as the fourth key step. This disconnection scheme represents Yang s specific approach using key chemical transformations such as radical cyclization (see sec. 13.7). Clearly, other disconnections are possible, and at each stage other disconnections could lead to alternate synthetic trees. 

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