Chapter 13, Problem 13.51P

Interpretation Introduction

Interpretation:

How to carry out the given synthesis using any reagents necessary, paying attention to the stereochemistry in the target to determine the required stereochemistry of the starting material, is to be proposed.

Concept introduction:

Synthesis may be designed by thinking in the reverse direction, from the product to the starting compound in a method called retrosynthesis. Retrosynthesis involves starting with the product and determining a suitable precursor from which it can be synthesized, without considering specific reactions. The precursor must be a simpler molecule, which may or may not have a close structural relation to the target molecule. This process is repeated until an easily available (or easily prepared) precursor is reached. Each of these steps are called a transform. A synthesis is a specific sequence of chemical reactions that converts starting materials into the desired compound, called the target (or synthetic target).

Retrosynthetic analysis involves considering the reaction sequence in reverse. The analysis starts with the product, determining the precursor that can produce it when the reaction is carried out in the forward direction. The retrosynthesis step, called a transform, does not consider a specific reaction or reaction conditions for the reaction in the forward direction. The transform is represented by an open arrow ($\Rightarrow$). It is a proposed undoing of a single reaction and dissects the target into a simpler precursor. This process is continued till an easily available or easily synthesized precursor is reached. The synthesis in the forward direction is then determined on the basis of the structural differences and the functional groups to be incorporated or modified. The specific reaction and reaction conditions are determined at this stage.