[Masurium]

I am looking for a good synthesis of 3-cyclohexenone.
Apparently, this could be accomplished by treatment of 1-methoxy-1.4-cyclohexadiene with 70% HClO4, but the cyclohexadiene is expensive, and I don't want to do a Birch reduction of anisole to make this compound. I could make 3-cyclohexenol from 1.4-cyclohexanediol, or by a Diels-Alder reaction of vinyl acetate and butadiene, but then I would need to oxidize the OH. I suppose if I had ketene available I could also effect the reaction with butadiene and should obtain the compound directly.
Does anyone have a suggestion about a relatively trouble-free method?
Thank you in  advance!
Masurium

[orgopete]

Puchase?
http://www.sigmaaldrich.com/catalog/product/aldrich/c102814?lang=en&region=US

[sjb]

Puchase?
http://www.sigmaaldrich.com/catalog/product/aldrich/c102814?lang=en&region=US

Wrong regioisomer (though I appreciate that the synthetic suggestions listed point that way too)?

OP, can you confirm if it is or that you're after?

[orgopete]

Okay, I missed that. I just skimmed through and thought it would give 2-cyclohexenone. None the less, I think I'd look up the literature methods. If there is only one, there may be a reason. If there are several, that may also indicate the submitters were not too pleased with the prior methods. I'd even assume they actually tried the literature methods before developing their own.

I cannot determine which is the better course of action, five minutes in the laboratory to save a week in the library or five minutes in the library to save a week in the lab. Needless to say, I don't know anything.

[Masurium]

sjb:
I started counting on the carbonyl, hence the compound I am after is the one on the right with an isolated double bond.

[Masurium]

orgopete:
Thank you for your suggestions. I have already spent quite some time in the library with that problem (a very enjoyable activity for me). The easiest way would be a Diels-Alder reaction of butadiene + ketene, a ketene acylal or ketene acetal or butadiene + vinyl acetate with subsequent conversion of the cyclohexenol acetate to a ketone. Unfortunately, the cycloaddition with vinyl acetate leads to less than 10 % of the required product (Diels and Rickert, Ann. (1940)). I don't have a ketene lamp, and the necessary ketene derivatives are not that easy to come by.

[sjb]

I would imagine that you would have to be very careful as this (the β,γ-unsaturated enone) is relatively unstable compared to the α,β-enone.

What do you need it for? If this is some retron maybe there are other ways of doing the retrosynthesis that form more viable intermediates.

[orgopete]

orgopete:
Thank you for your suggestions. I have already spent quite some time in the library with that problem (a very enjoyable activity for me). The easiest way would be a Diels-Alder reaction of butadiene + ketene, a ketene acylal or ketene acetal or butadiene + vinyl acetate with subsequent conversion of the cyclohexenol acetate to a ketone. Unfortunately, the cycloaddition with vinyl acetate leads to less than 10 % of the required product (Diels and Rickert, Ann. (1940)). I don't have a ketene lamp, and the necessary ketene derivatives are not that easy to come by.

That looks like why I assumed you wanted the isomer. Getting the non-conjugated isomer is probably difficult. Finding a lit prep demonstrates successful methods. It has a CAS RegNo so finding methods shouldn't be difficult. The finding, not necessarily the preps.

I see there seem to be a number of patents in which 3-cylcohexenone is mentioned. Is that the interest here?

[Masurium]

The compound is indeed touchy and rearranges easily, as seen in the preparation by Hanack (Ber. 96, 2937 (1963).

I would imagine that you would have to be very careful as this (the β,γ-unsaturated enone) is relatively unstable compared to the α,β-enone.

What do you need it for? If this is some retron maybe there are other ways of doing the retrosynthesis that form more viable intermediates.