2,5-Dimethoxy-4-Bromobenzaldehyde will indeed condense with nitroethane to form 2,5-Dimethoxy-4-Bromophenyl-2-nitropropene, and neither sodium borohydride or aluminum amalgam will dehalogenate it to any noticeable extent under normal conditions.
2,5-Dimethoxy-4-bromobenzaldehyde12,5-Dimethoxybenzaldehyde (66.5 g, 0.4 mole) was dissolved in 300 ml of CH
2Cl
2. Anhyd SnCl
4 (115 g, 0.44 mole) was added, followed by 64 g of Br
2 over a 1-hr period. The resulting solution was refluxed for 2 hr arid stirred overnight at room temp. The orange suspension was poured over 500 g of ice, and the layers were separated. The CH
2Cl
2 layer was washed with 10% NaHCO
3 and H
2O and dried (Na
2SO
4). After filtration the solvent was removed in vacuo, and the solid residue recrystd from MeOH-H
2O to yield 64g (66%) of the aldehyde, mp 132-133°C.
1-(4-bromo-2,5-dimethoxyphenyl)-2-nitropropene12,5-Dimethoxy-4-bromobenzaldehyde was refluxed with EtNO
2 and NH
4OAc in AcOH as described by Gairaud and Lappin
2 to give a 57% yield of 1-(4-bromo-2,5-dimethoxyphenyl)-2-nitropropene, mp 113.5-115°C.
Condensations with ammonium acetate in acetic acid2The aldehyde (5g), 5 ml of the nitroalkane, and 2 g. of ammonium acetate were added to 20 ml of glacial acetic acid. The resulting solution was refluxed for two hours and then poured into ice-water. If a solid product was obtained it was collected and recrystallized from methanol, ethanol, or acetic acid. If the product was an oil it was separated and crystallized, if possible, from one of the above solvents.
References:[1] J. Med. Chem. 14(4), 370-372 (1971)
(
https://www.thevespiary.org/rhodium/Rhodium/pdf/nichols/nichols-bromomethoxyamphetamines.pdf)
[2] Gairaud and Lappin, JOC 18, 1 (1953)
(
https://www.thevespiary.org/rhodium/Rhodium/chemistry/nitrostyrenes.gairaud-lappin.html)