Nitroalkene reduction using trialkylborohydrides

[demorol]

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

[demorol]

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