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Benzaldehyde + MEK acid catalyzed aldol

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lugh:
In this article, p2p is synthesized by oxidation of trans beta methyl styrene in yields of over 90%  :)

On the Mechanism of the Bayer-Villiger Oxidation of Ketones by Bis(trimethylsilyl) Peroxomonosulfate. Intermediacy of Dioxiranes
Camporeale, M.; Fiorani, T.; Troisi, L.; Adam, W.; Curci, R.; Edwards, J.O., J. Org. Chem., 55 93-8 (1990)



8)

bio:
Thanks for finding that , lugh. Any chance of locating the 3rd one nOOdle posted?

What I'm not entirely sure about is if the epoxide was made from the MePhBuO rather than the ester would it hydrolyse to the same product (2propanone)? Would try this if there is a known procedure similar enough to be adapted to the MPB.

 Am thinking of using chromics HCl  rearrangement procedure for the hydrolysis of the ester. Is this really adaptable as is to unsaturated ketonic ester hydrolysis? Having a hard time finding one that uses acid instead of base. Vogel mentions sulfuric acid in acetic acid for ketonic ester hydrolysis but no experimental except for many base examples.

Also in the 90% article,  J. Org. Chem., 55, 93-98 (1990),  the trans beta methyl styrene is also called propenyl benzene, correct?

Rhodium:
trans-?-methylstyrene is also called propenylbenzene, correct?

Correct.

psychokitty:
First of all, the hydrolysis occurs in most publications that I've read using KOH, NOT NaOH.  Maybe that'll make the difference.

As for recommendations as to how the syntheses protocol can be modified to advantage, it would seem that using potassium (or perhaps sodium) acetate in the peracetic acid reaction is the ticket.  Apparantly, it allows the reaction to complete in shorter time (1 HOUR!), with fewer side-reactions, and overall better yields.   Also, use of a saturated acetate salt mixture allows substituted (as in methylenedioxy-substituted) a,B-unsaturated ketones to be used as precursors to ring-substituted enol-esters, which are produced in good yield. 

As for the dilution factor, in many of the articles that I've read (already mentioned), the percentage of acetic acid doesn't seem to impact the final yield of product, so my best guess is that Chromic's method should work well if not wonderfully.  The only catch is the use of a halohydrocarbon solvent as part of the biphasic peracid reaction mixture.  While this works wonders for making epoxides and diols out of alkenes, I wonder what it's effect will be when applied to the Baeyer-Villiger reaction.  DCM/performic acid has already been published as an effective reagent for the Baeyer-Villiger reaction using ketones as precursors.  But I have yet to find even one publication describing its use as  would be applied to a,B-unsaturated ketones.

Aside from the acetate salt issue, lowering the temperature of the reaction to about 0°C seems to be the only other factor which might merit modification.

Let me know if you have any additional questions, anyone.

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