Page 171 - Catalysts for Fine Chemical Synthesis Vol 1 - Robert & Poignant

158 hydrolysis, oxidation and reduction

Materials and equipment

. 2-Bromo-(3-nitro-4-benzyloxy)acetophenone, 100 g
. Anhydrous tetrahydrofuran, 800 mL
. (1R,2S)-Aminoindanol-oxazaborolidine
. Acetone, 100 mL
. Toluene, 700 mL
. Aqueous 2 % sulfuric acid solution, 350 mL
. Aqueous 20 % NaCl solution, 160 mL
. Heptane, 200 mL
. Heptane, 200 mL
. 1 L Round-bottomed flask with a magnetic stirrer bar
. Magnetic stirrer
. Separatory funnel (2 L)
. Rotary evaporator
. Buchner funnel

Procedure
1. The oxazaborolidine solution was cooled to 0 8C.
2. A solution of bromoketone 3 in tetrahydrofuran (100 g in 800 mL THF,
0.35 M) was slowly added over 1 hour to the oxazoborolidine solution while
the temperature was maintained between 0±5 8C. The mixture was stirred for
30 minutes at 0 8C.
3. Acetone (100 mL) was slowly added to quench the excess borane. The reaction
mixture was concentrated to 300 mL and toluene (700 mL) was added.
The solution was washed with 2 % sulfuric acid (350 g) then with 20 %
NaCl (120 g). The organic phase was concentrated to 300 mL and cooled to
5 8C.
4. The resulting slurry was stirred at 5 8C for 1 hour, heptane (200 mL)
was slowlyadded and the mixture was stirred an additional 1 hour at
5 8C.
5. The slurry was filtered and the solid was washed with heptane (200 mL). The
off-white solid was dried in vacuo to give 89 g (93 % ee, >99 % cp) of the
desired alcohol.

Recrystallization of 2-bromo-(3-nitro-4-benzyloxyphenyl)ethanol
Materials and equipment

. 2-Bromo-(3-nitro-4-benzyloxy)acetophenone, 48 g
. Toluene, 100 mL
. Heptane, 125 mL

. 500 mL Round-bottomed flask with a magnetic stirrer bar