Principles of Organic Synthesis  Modern Synthesis  A multi-step
synthesis of any organic compound requires the chemist to
accomplish three related tasks:       1. Constructing the carbon
framework or skeleton of the desired molecule.       2.
Introducing, removing or transforming functional groups in a
fashion that achieves the functionality of the desired compound.
      3. Exercising selective stereocontrol at all stages in
which centers of stereoisomerism are created or influenced.
These are not discrete independent tasks to be attacked and
solved in turn, but must be integrated and correlated in an
overall plan. Thus, the assembly of the molecular framework will
depend in part on the structure and functionality of available
starting materials, the selectivity (regio and stereo) of the
various reactions that may be used to stitch them together, and
the loss or relocation of functional groups in the intermediate
compounds formed on the way to the final product.  Other factors
must also be considered, always