Synthesis of 3,4-methylendioxybenzylmethylketone from piperonal (glycide ester route)(small scale)

WillD

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Step 1. PMK-glycidate.
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1. Freshly prepared powdered sodium ethoxide (23 g.) was added during 4 hours to a stirred mixture of piperonal (50 g.) and ethyl a-bromopropionate (61 g.), cooled in ice-salt.
2. Stirring was continued overnight at room temperature and for 6 hours on the water-bath; ice-water was then added, and the mixture acidified with dilute acetic acid.
3. The glycide ester was extracted with ether, and ethereal solution washed with aqueous sodium carbonate and dried with sodium sulphate.
4. After removal of ether, the residue was distilled and collected between 70 *C and 200* at 20 mm.
5. Subsequent redistillation gave B-3,4-methylenedioxyphenyl-a-methylglycide ester (40 g.) b.p. 184-186*/14 mm (yield, 48%).


Step 2. 3,4-methylendioxyphenylacetone.
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1. The ether (35 g.) was refluxed for 5 hours with a solution of sodium hydroxide (10 g.) in 90% aqueous alcohol (150 ml).
2. After removal of part of the alcohol by distillation, the residue was diluted with a large volume of water and extracted with ether, and with the addition of a trace of copper powder;
3. The liquid was then distilled slowly under reduced pressure in the presence of copper powder. Redistillation of the product gave 3,4-methylenedioxybenzylmethylketone (11,1 g.) b.p 154-156/11 mm. (yield, 44.5%).
 
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WillD

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This synthesis of glycidat works, but for hydrolysis would better use hydrochloric acid. And bromopropionate can replace to chloropropionate.
 

Montecristo

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Alternatives for ether?
 

btcboss2022

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Step 1. PMK-glycidate.
View attachment 1477

1. Freshly prepared powdered sodium ethoxide (23 g.) was added during 4 hours to a stirred mixture of piperonal (50 g.) and ethyl a-bromopropionate (61 g.), cooled in ice-salt.
2. Stirring was continued overnight at room temperature and for 6 hours on the water-bath; ice-water was then added, and the mixture acidified with dilute acetic acid.
3. The glycide ester was extracted with ether, and ethereal solution washed with aqueous sodium carbonate and dried with sodium sulphate.
4. After removal of ether, the residue was distilled and collected between 70 *C and 200* at 20 mm.
5. Subsequent redistillation gave B-3,4-methylenedioxyphenyl-a-methylglycide ester (40 g.) b.p. 184-186*/14 mm (yield, 48%).


Step 2. 3,4-methylendioxyphenylacetone.
View attachment 1478

1. The ester (35 g.) was refluxed for 5 hours with a solution of sodium hydroxide (10 g.) in 90% aqueous alcohol (150 ml).
2. After removal of part of the alcohol by distillation, the residue was diluted with a large volume of water and extracted with ether, and with the addition of a trace of copper powder;
3. The liquid was then distilled slowly under reduced pressure in the presence of copper powder. Redistillation of the product gave 3,4-methylenedioxybenzylmethylketone (11,1 g.) b.p 154-156/11 mm. (yield, 44.5%).
William DampierCould be copper replaced by any other metal? Iron, Aluminum...?
Thanks.
 

Fring

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@William Dampier , the second part would be only applicable for the non ethyl pmk that we have now , right?
 

WillD

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For any glycide ether, everything should be the same. Methyl, ethyl, propyl, tert-butyl, etc - the same
 
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