Page 165 - Catalysts for Fine Chemical Synthesis Vol 1 - Robert & Poignant

152 hydrolysis, oxidation and reduction

. N, O-Bis-(trimethylsilyl)-acetamide (BSA), 924 mL, 3.74 mmol, 1.1 eq
. Dry acetonitrile, 15 mL
. Dry tetrahydrofuran, 18 mL
. n-Butyl lithium, 1.6 M in hexane, 2.1 mL, 3.4 mmol, 1 eq
. Benzophenone, 682 mg, 3.74 mmol, 1.1 eq
. Aqueous saturated solution of NH 4 Cl and methanol (10:1), 2 mL
. Petroleum ether, ethyl acetate
. p-Anisaldehyde dip
. Silica gel 60 (0.063±0.04 mm)

. 50 mL Two-necked round-bottomed flask with a magnetic stirrer bar
. 50 mL Schlenk tube with a magnetic stirrer bar
. Condenser
. Cannula (double-tipped needle)
. Magnetic stirrer hot plate with a thermostatically controlled oil bath and
thermometer
. Ice-bath
. Syringe
. Solid carbon dioxide/ethanol cooling bath (ÿ78 8C)
. Kugelrohr apparatus

Procedure
1. A 50 mL two-necked flask equipped with a magnetic stirrer bar was dried
overnight at 150 8C, cooled under vacuum and flushed with nitrogen.
2. Under a nitrogen atmosphere, the flask was charged with (SS)-methyl-S-
phenylsulfoximine (523 mg) and placed under vacuum. The flask was
flushed with nitrogen, then dry acetonitrile (15 mL), and N, O-bis-(tri-
methylsilyl)-acetamide (924 mL) were added.
3. The flask was equipped with a condenser and the mixture was heated under
nitrogen at 50 8C and stirred for 45 minutes at this temperature (it was not
necessary for the solvent to reflux).
4. After 45 minutes, the mixture was cooled to room temperature under nitro-
gen. The solvent was evaporated under high vacuum.
5. The residue was placed under nitrogen in a Kugelrhor apparatus and the
impurities were distilled at a temperature less than 70 8C at 0.3 mbar. The
purity of N-(trimethylsilyl)-S-methyl-S-phenylsulfoximine was verified by
NMR.
. 1 H NMR(200 MHz, CDCl 3 ): d 7.97±7.93 (m, 2H, Ph); 7.57±7.451 (m, 3H,
Ph); 3.01 (s, 3H, CH 3 ); 0.11 (s, 9H, Si (CH 3 ) ).
3
6. A 50 mL Schlenk tube equipped with a magnetic stirrer bar, dried overnight
at 150 8C, was cooled under vacuum and then flushed with nitrogen.
7. N-(Trimethylsilyl)-S-methyl-S-phenylsulfoximine (prepared as above) was
dissolved in 15 mL of dry tetrahydrofuran and transferred by cannula into
the Schlenk tube under nitrogen.