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        MDP2P from piperonal via 3,4-Methylenedioxyphenyl-2-nitropropene
                                    by Karel
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Here is announced experimental from JOC 221 (1951):

In a 5-liter 3-necked flask equipped with a stirrer and reflux condenser were
placed 1000 cc. of ethanol and 110 g of beta-nitroisoeugenol. The mixture was
heated with stirring and, when the nitroisoeugenol was dissolved, 2500 cc. of
hot water was added. With heating and vigorous stirring, 200 g of reduced iron
powder and 8 g of hydrated ferric chloride were added. With continued stirring
100 cc. of concentrated hydrochloric acid was added slowly. The hydrochloric
acid caused a violent reaction which subsided after about 5 minutes; the mixture
was refluxed with stirring for two hours and then distilled under reduced
pressure until approximately 2 liters of distillate was collected. The residue
was filtered, and the fluffy iron oxide was washed thoroughly with hot water and
then with ether. The combined filtrate and washings were acidified strongly with
hydrochloric acid and extracted with ether. The ether was dried and distilled to
yield a light oil which was fractionated in vacuo to give 68 g of vanillyl
methyl ketone boiling at 126-127 C at 0.3 mm (72 % yield).

3,4-Dimethoxyphenylacetone and 3,4-methylenedioxyphenylacetone were prepared
from the corresponding beta-nitropropenylbenzenes by almost identical procedures
with 90 and 72 % yield.

For preparation of 4-methoxyphenylacetone with toluene/water as solvent see
Organic Syntheses, Coll. vol. 4, p. 573.

My modification of this preparation:

In a 2-liter 3-necked flask equipped with a stirrer and reflux condenser were
placed 460 ml of ethanol (1) and 67 g of beta-nitroisosafrole (2). The mixture
was heated with stirring and, when the yellow crystals were dissolved, 1100 ml
of hot water was added. With heating and vigorous stirring, 80 g of reduced iron
powder (3) and 5 g  FeCl3+6H2O were added. With continued stirring 63 ml conc.
HCl was added in 30 min. The mixture was refluxed with stirring for 2 h and then
distilled under atmospheric pressure (4). The residue was filtered and brown
iron oxide was extracted 3 x 50 ml CH2Cl2. Filtrate and organic washings were
acidified with HCl and red ketone layer was collected. Light green water layer
was extracted 2 x 100 ml CH2Cl2. The combined extracts were dried with Na2SO4
and distilled at atmospheric pressure (80 C bath). Dichloromethane was
completely removed in vacuo to give 55 g of crude MDP2P as deep red oil which
was used for CH3NH2/Al reaction.

1. Use of methanol instead of ethanol led to incomplete dissolution of yellow
   crystals.

2. Beta-nitroisosafrole can be conveniently prepared by Knoevenagel:
   150 g of piperonal was mixed with 76 ml nitroethane (piperonal should
   completely dissolve to give colourless liquid) and 1.5 ml of n-butylamine
   (or n-pentylamine) was added. Resulting yellow solution was held in a dark
   place; some water started appear after 2-3 days as the reaction proceeded.
   Light orange crystals of product started precipitate after 6-8 days. After 20
   days a mixture was filtered. Light brown filtrate was filtered again after 5
   days to afford next crop of product. Yield 85 - 90 % of light orange
   crystals, which are suitable for preparation of the ketone.

3. An iron reduced with hydrogen was used. Use of 20 mesh iron powder instead of
   reduced iron led to less vigorous reaction, resulting ethanol didn't contain
   NH3 and ketone was contamined with about 20 % of its oxime (not quantitative
   reduction).

4. A fraction 77 - 85 C was collected. It contained some NH3 which can be
   neutralized with conc. H2SO4 and distilled again via Vigreux column.
   Resulting 90 % ethanol was used for preparation of the next portion of ketone.

Good luck.

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