Carbon-carbon bond forming reactions

Many of the reactions seen in this chapter involve carbon-carbon bond forming reactions, which often represent the key steps in multistep syntheses.  This is because this chapter showed the use of strongly nucleophilic carbon (Organometallics, Wittig reagents or enolates) reacting with the electrophilic carbon of the C=O. 

The chart below shows how to design a synthesis for the most suitable carbon-carbon bond formation. It uses a five-carbon target as a standard model; you should adapt it to your specific carbon skeleton.  The product is shown on the left, and the squiggly arrow shows the “disconnection,” equivalent to the bond that will be made in the synthesis (shown as a dashed line).  The => arrow means “is made from.”