demorol
(Hive Bee)
01-01-03 17:15
No 394699
      Nitroalkene reduction using trialkylborohydrides
(Rated as: excellent)
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I think someone was asking for this article in the Serious Chemistry forum. Well, here it is!

Reduction of alpha,beta-Unsaturated Nitroalkenes with Trialkylborohydrides: A Synthesis of Ketones

Phenylacetone from 2-Nitro-1-phenylpropene; Typical Procedure

Lithium tri-sec-butylborohydride (11mL of 1 M solution in THF, 11 mmol) is placed in a flame-dried, nitrogen-flushed, 100mL RB flask equipped with a septum inlet and a magnetic stirring bar. A solution of 2-nitro-1-phenylpropene (1.63g, 10 mmol) in THF (10mL) is added dropwise to a stirred solution of the trialkylborohydride at room temperature. A mildly exothermic reaction ensues with the disappearance of yellow coloration (nitroalkene). The mixture is stirred for 30 minutes and then poured into cold (-10 C) 4 M sulfuric acid (50mL). Ice/water (100mL) is carefully added to the mixture which is stirred for 10 minutes. The product is extracted with ether (3 50mL). The combined ether extracts are washed with water (2 50mL), dried with magnesium sulfate and evaporated under reduced pressure. The crude product is purified by column chromatography (silica gel; 4% ether/petroleum ether eluant) to give 1-phenyl-2-propanone as an oil; yield 1.1g (80%); mp of 1-phenyl-2-propanone semicarbazone: 187-188 C.

Reference: Synthesis, 1985, No. 6/7, pp 654


I'm dreaming of the white crystals.
 
 
 
 
    demorol
(Hive Bee)
01-06-03 20:09
No 395857
      This is not a reduction procedure, but I ...  Bookmark   

This is not a reduction procedure, but I didn't want to open new thread for posting this synthesis. It is an ordinary synthesis for obtaining 1-phenyl-2-nitropropene. I haven't found the below reference in TFSE so I assume it hasn't been posted before.

1-phenyl-2-nitropropene

A solution of benzaldehyde (6.4g, 60 mmol) and ammonium acetate (1g, 13 mmol) in nitroethane (20mL, 280 mmol) was heated to reflux for 5 h. On cooling, after removal of solvent, the residue was purified by column cromatography on silica gel 60 N (neutral; hexane/chloroform; 2:1, v/v), then recrystallized from hexane to give 1-phenyl-2-nitropropene as a light yellow crystal. Yield: 6.2g (63%), mp 71-73 C.

Reference: J. Chin. Chem. Soc., Vol. 49, No. 4, 2002


I'm dreaming of the white crystals.