4.
Making your life easier: Sorting your synthetic tools
There
are pretty much two types of synthetic tools available to
you: (1) carbon-carbon bond forming reactions, and (2) functional
group reactions that convert one functional group into another
(like a reaction that converts an alcohol into a ketone, for
example).
You may
have noticed that many, many multistep syntheses involve making
carbon-carbon bonds (which, in turn, you will have noticed
by comparing the carbon skeleton of the starting material
and product as suggested in a previous tip). In the toolbox
of all your reactions, these carbon-carbon bond forming reactions
should go right on the top where they are easy to reach. The
functional group transformations are of more secondary importance
and go on the bottom of the toolbox to be dusted off when
needed.
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Synthetic
toolbox. |
Step
1: Compiling a list of all the carbon-carbon forming reactions
you've learned.
Carbon-carbon
reactions are your primary tools to build up your molecules,
and are perhaps the most important and valuable reactions
to remember. Once you know which carbon-carbon reactions to
use to make the product, the other reactions often seem to
magically fall into place.
At first,
your list of carbon-carbon forming reactions will be small.
But this list will get bigger. At the end of your first semester,
you may have a list that contains some of the following carbon-carbon
reactions (and perhaps others, depending on what material
your professor and textbook chooses to cover):
Later
(second semester typically), you may add enolate and enol
reactions to the list (like the aldol reaction, Claisen
reaction, Michael reaction, etc).
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