The easiest way for me to determine a starting product for a cyclization
problem is to look at where the double bond is in the cyclic final
product. You know that this is where the ends of the dialdehyde, keto
aldehyde, or diketone connected. After breahing this bond, you can
determine which end attacked the other. Look at the where the carbonyl
group is. this is the part of the molicule that attacked the other
end because it had some sort of alpha hydrogen that was removed. remember
that five and six membered rings are favored over anything smaller. So if
the attacking group is a ketone, either one of the carbons adjacent to
the carbonyl could be the alpha carbon. After you have determined all of
these things, all youhave todo is ad the hydrogens that were removed, and
put in the double bonded oxygen in on the carbon that was attacked.
I hope this sheds some light on things!
justin
On Tue, 21 Oct 1997 rorabajh@plu.edu wrote:
>
> I've been looking over all of the question marks I had in the columns of
> my chapter problems, so if you could look over yours for the next few
> questions I am about to ask, I would really appreciate it.
>
> 17.17 (c):
> could someone explain to me how they are able to come up with the
> structures of the reactants to make cyclic compounds? Is there some
> general rule I can follow? Problem 17c just stuck out in my mind as being
> extra tricky; could someone kind of walk me through the process of
> figuring this out?
>
> -jenny
>
>