4-amino-2-bromo-3,6-dimethylphenol

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Into a dry 250 milliliter round bottom flask equipped with a magnetic stirrer and nitrogen inlet was added 4-amino-2-bromo-3,6-dimethylphenol (11.94 grams, 55.3 mmol) prepared in Part B and dry dimethylsulfoxide (118 milliliters). Potassium t-butoxide (7.26 grams, 64.65 mmol) was added portionwise under nitrogen and the mixture was stirred at room temperature for 0.5 hours. Solid 3,4-dichloronitrobenzene (13.33 grams, 70.52 mmol) was then added and the reaction mixture was heated at 50° C. for 48 hours. After cooling the mixture was diluted with toluene and washed successively with saturated NH4Cl solution (3x) and with 5% NaOH solution until the aqueous washes remained colorless. This was followed by washes with water and brine, drying over Na2SO4 and solvent removal under reduced pressure to afford the crude product (9.4 grams) as a dark red-brown oil. Flash column chromatography on 650 grams of silica gel (3:1 hexane:ethyl acetate) afforded pure 3-bromo-4-(2 -chloro-4-nitrophenoxy)-2,5-dimethylaniline (4.7 grams, 12.6 mmol, 23%) as a yellow-brown solid. H'-NMR (CDCl3) 8.42 (d, J=2 Hz, 1H), 8.01 (d,d; J=2, 9 Hz; 1H), 6.55 (d, J=9 Hz, 1H), 6.58 (S, 1H), 3.73 (brS, 2H), 2.28 (S, 3H), 2.06 (S, 3H). Into a dry 250 milliliter round bottom flask equipped with a magnetic stirrer and nitrogen inlet the reaction mixture was heated at 50° C. for 48 hours After cooling the mixture washed successively with saturated NH4Cl solution (3x) and with 5% NaOH solution until the aqueous washes drying over Na2SO4 and solvent removal under reduced pressure to afford the crude product (9.4 grams) as a dark red-brown oil

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Into a Parr bottle was charged 2-bromo-3,6-dimethyl-4-nitrophenol (13.6 grams, 55.3 mmol) prepared in Part A and ethyl acetate (50 milliliters). The reaction vessel was purged with nitrogen and 5% platinum on carbon (1.36 grams) was added immediately following the purge. Hydrogenation was carried out on a rocking Parr hydrogenator for 1.5 hours at 40-50 psi hydrogen and room temperature. The reaction mixture was filtered through celite and concentrated under reduced pressure to give 4-amino-2-bromo-3,6-dimethylphenol as a brown solid in quantitative yield. H'-NMR (CDCl3 -DMSO-d6), 6.40 (S, 1H), 2.17 (brS, 6H). The reaction vessel was purged with nitrogen and 5% platinum on carbon (1.36 grams) was added immediately The reaction mixture was filtered through celite and concentrated under reduced pressure