[a confused chiral girl]

I am trying to write out the steps for this reaction. I tried to start with HBr, and H2SO4..but I am totally stuck. I don't know how to find the steps for this reaction nor give the reageants that is required in order to get this product.

Thank you!! 

[Chudasama]

react your starting dicarbonyl compound with sodium ethoxide to remove the most acidic proton (one in between the carbonyls)

react this with CH3CH2CH2CH2-I

add NaOH + HCl to convert the ester into a carboxylic acid

heating this compound expels CO2 leaving you with an enol

this enol is in a tautomeric equilibrium with the product ketone (nb: equilibrium is highly in favour of the ketone)

(see attachment)

[a confused chiral girl]

thank you for taking the time to help me draw it out. it is very clear. but, how come you know it so fast?? I spent over 3 hours (not continuoulsy) trying out this question, and never thought of it the way you did. I kept trying HBr which is the most common reagent. are you a professor??

[movies]

This is a variant of the acetoacetic ester synthesis, it's been around for a long time!

This was the way to alkylate ketone compounds before powerful bases like lithium diisopropyl amide gained popularity in the 1960s.

Also, this is a classic sophomore organic chemistry question.  I submitted a nearly identical question for an exam when I was a TA last year.

[Chudasama]

thank you for taking the time to help me draw it out. it is very clear. but, how come you know it so fast?? I spent over 3 hours (not continuoulsy) trying out this question, and never thought of it the way you did. I kept trying HBr which is the most common reagent. are you a professor??

nah...lol...i'm not a professor, just in my third year at uni....the only reason i was able to answer the question was because i had seen a similar transformation in a lecture i had last year.

in general though... whenever i see a beta-keto-ester as a starting reagent and a product which has only one carbonyl i tend to think of this type of reaction transformation

[Custos]

in general though... whenever i see a beta-keto-ester as a starting reagent and a product which has only one carbonyl i tend to think of this type of reaction transformation

Good call .

Confused chiral girl, the basis of synthetic organic chemistry is building carbon skeletons. To do this we use functional groups (ketones, esters, aldehydes, double bonds, halides etc.) as "handles" to activate carbon atoms to assist in forming carbon-carbon bonds. Carbonyls are great because they help stabilise a negative charge on the carbon next to them - i.e. a strong base will generally abstract a proton next to a carbonyl group. Two carbonyls on either side of a carbon makes that even easier. Negative charges, thus generated are nucleophilic and will attack other carbonyls, alkyl halides, vinyl halides, etc.... anything that is electrophilic, to form a new carbon-carbon bond.

Finally, once you have used one of these functional group "handles" to help form your new carbon-carbon bond you might want to get rid of it. Esters can be hydrolysed to acids which can (sometimes) be decarboxylated, ketones can be reduced to alcohols and (sometimes) eliminated to give a double bond, which can in turn be hydrogenated, and so on. It's really an extensive and powerful toolbox of reactions that can be used to build up carbon frameworks. Once you understand how the tools work, you start to recognise where to use them. Like most puzzles, the easiest way is to work backwards from your solution (the product) to the starting materials. This is a whole philosopy of organic synthesis called the "disconnection approach".

As with most puzzles, you can stare at them for hours in frustration and then when you see the solution it all seems very obvious. Practice helps. Don't panic, it can be fun.