Geomancer
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Cyclobutanone?
In the notes to the orgsyn procedure, several other methods were mentioned. One method not mentioned was the reaction of acetone with methylene halide
with basic catalyst. Why won't this work?
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Turel
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If
If it worked, wouldn't that be prone to give Cycloocta-1,5-dione?
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Marvin
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Base catalysed self condensation of the acetone?
Ring strain in the 4 membered product preventing closure?
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BromicAcid
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I don't see why this would work. Under basic conditions the acetone will form the enolate but where to go from here. The methylene chloride is
fairly unreactive and those chlorine on there are not going to just split off for no reason. The enolate will not attack methlyene chloride and it
won't attack the enolate, you have a stale mate unless there were some extensive pressures involved.
The chlorine block most avalible pathways for this reaction on carbon, it's not like SiH2Cl2 which would react due to the d orbitals which carbon
lacks. The only reaction might be a variation of the chlorobutanol reaction of chloroform and acetone if the base was present in somewhat gross
excess.
But then again organic chemistry is not my thing.
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Turel
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Not True
1.He never specified DCM. He said methylene dihalide. CH2I2 is more sterically hindered than DCM, but historically works better in substitution
reactions due to greater polarity and weaker bond strength.
Enol will indeed attack DCM in high enough concentration and exposure, i.e. strong enough base and use of a PTC. The problem is competition between
base and enol for the substitution.
Marvin had it right on the button, the ring is far too strained to be so easily constructed. The enol route would give several products, but none
would be the desired one.
-T
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Geomancer
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Yeah, that steric thing had me worried. Check out OS CV 6, 316 though. Would seem to have the same problems, but the yield is claimed at 65-84% in
refluxing THF. Would acetone self-condensation really be a problem? My understanding was this rapidly equilibrates as long as you don't remove
the water.
So, it looks like you go from cyclopropanes, then. Lots of interesting chemistry here. Would the alcohol group of allyl alcohol offend the
delicate organometallic sensibilities of the Simmons-Smith reagent?
One really slick possibility would be to use a Kishner synthesis starting from a straight chain 4 carbon sugar-type thing. Say, take erythritol,
etherify one of the terminal hydroxys (how?), cook with sulfuric acid, then cook the product with hydrazine. Or go through erythrose, reducing
somewhere along the way, perhaps similar to the synthesis of allyl alcohol from glycerine (that would be a trick). You could, of course, get the
Kishner precursor from acetone and formaldehyde, but that's no fun.
I'm not particularly interested in actually doing any of this. Just a mental exercise, looking for surprising routes to butyrolactone. Any
ideas?
[Edit: added white space since this program won't let me indent my paragraphs]
[Edited on 8-3-2004 by Geomancer]
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GeneralChemTutor
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| Quote: |
In the notes to the orgsyn procedure, several other methods were mentioned. One method not mentioned was the reaction of acetone with methylene halide
with basic catalyst. Why won't this work?
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Here are some reasons.
The base can also react with the methyl halide through SN2.
The enolate is a strong base, difficult to pull of the alpha hydrogen (you don't want to use a strong base for SN2 reactions). Instead use the
synthetic equivalent, activated hydrogen compound, acetoacetate.
Also, the simplest reason of all, there are better methods.
p.s. acetone does not self condensate, the carbonyl carbon is not as electrophilic as aldehydes.
-------------------------
Online Chemistry Resources
http://groups.msn.com/GeneralChemistryHomework
[Edited on 9-3-2004 by GeneralChemTutor]
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Polverone
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acetone does condense
Warmed (or even room-temperature) acetone will form a variety of condensation products under the influence of strong acids or bases. This can produce
mesitylene, phorone, diacetone alcohol, and mesityl oxide (possibly others?).
PGP Key and corresponding e-mail address
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GeneralChemTutor
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| Quote: |
Warmed (or even room-temperature) acetone will form a variety of condensation products under the influence of strong acids or bases. This can produce
mesitylene, phorone, diacetone alcohol, and mesityl oxide (possibly others?).
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Of course, but It's not of synthetic utility...also in room temperature (or even if warmed) not in good yields; other reactions take place also
at higher temperatures.
[Edited on 10-3-2004 by GeneralChemTutor]
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Geomancer
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Thanks for reminding me about acetoacetate. Using acetonedicarboxylic ester might be advatageous. Crappy atom economy, though.
I don't see why the catalyst would interfere if one were to use a non-nucleophilic base. Unless that Orgsyn reference operates by some really
strange mechanism (sulfur chemistry is not my forte), I'm actually thinking this might work, with possible miserable yields.
The erythrose route, if it were to exist, is more surprising though. The transformation (to butyrolactone) would take one straight 4C chain to
another straight 4C chain, but with the carbon atoms in a completely different order!
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