Page 97 - Catalysts for Fine Chemical Synthesis Vol 1 - Robert & Poignant

epoxidation of allylic alcohols 83

. Poly(octamethylene-l(‡)-tartrate)
. Ti(OiPr) 4
. Anhydrous tert-butylhydroperoxide (TBHP) (in iso-octane).
See refs 5.6 for preparation and standardization
. (E)-Undec-2-en-1-ol (4, R ˆ C 8 H 17 )
. Diethyl ether, toluene, petroleum ether
. NaOH, NaCl, MgSO , Celite
4
. Three-necked round-bottomed flask
. Magnetic stirrer
. N 2 supply
. Gas bubbler
. Syringe
. Bu Ècher funnel, flask
. Filter paper
. ÿ20 8C Cold bath
. Rotary evaporator

Procedure
1. An oven-dried three-necked round-bottomed flask (100 mL) equipped with
a magnetic stir bar, nitrogen inlet, septum and bubbler was charged with
Ê
CH 2 Cl 2 (35 mL dried over CaCl 2 ), powdered activated 4 A molecular sieves
(0.3 g) and poly(octamethylene-l-(‡)-tartrate) (1.56 g, 0.0059 mol tartrate,
6 % branching). The flask was cooled to ÿ208C and Ti(OiPr) (0.85 g,
4
0.0030 mol) added via a syringe.
2. The mixture was stirred for 1 hour at ÿ20 8C and then anhydrous TBHP
(7.5 mL, 3.2 M in iso-octane) also added slowly via a syringe. The mixture was
again stirred at ÿ20 8C for 1 hour. (E)-Undec-2-en-1-ol (1 g, 0.0059 mol) in
CH 2 Cl 2 (5 mL) was added dropwise by syringe such that the temperature was
maintained between ÿ15 and ÿ20 8C. The reaction mixture was stirred at
ÿ20 8C for 6 hours and then placed in a freezer overnight.
3. The polymer±ligand±Ti complex was filtered off and washed thoroughly with
CH 2 Cl 2 . The recovered solution was then quenched with aqueous NaOH
(30 %, 10 mL, saturated with NaCl) and diethyl ether added (50 mL) after
which the cold bath was removed and the stirred mixture allowed to warm up
to 10 8C. Stirring was continued for 10 minutes at 10 8C whereupon sufficient
magnesium sulfate and Celite were added to absorb all the aqueous phase.
After a final 15 minutes stirring the mixture was allowed to settle and the
solution filtered through a pad of Celite and washed with diethyl ether. The
solvents were removed under vacuum and the excess TBHP removed by
azeotropic distillation with a little added toluene. The crude product was
purified by recrystallization from petroleum ether to yield a white solid
(0.55 g, 50 %).