R. A. Joshi et al. / Tetrahedron: Asymmetry 16 (2005) 3802–3806
3805
4.4. 1-Benzyloxy-4-(2-cyclopropylmethoxyethyl) benzene
5
IR (Neat): m 3080, 2934, 2859, 1648, 1611, 1583, 1511,
1
1425, 1378, 1241, 1177, 1097, 1021, 927, 827 cmÀ1; H
NMR (200 MHz, CDCl3): d 0.20 (m, 2H), 0.54 (m,
2H), 1.05 (m, 1H), 2.83 (t, J = 7.5 Hz, 2H), 3.31 (d,
J = 6.8 Hz, 2H), 3.64 (t, J = 7.5 Hz, 2H), 4.50 (d,
J = 5.3 Hz, 2H), 5.25 (d, J = 10.4 Hz, 1H), 5.50 (d,
J = 17.3 Hz, 1H), 6.05 (m, 1H), 6.75 (d, J = 8.7 Hz,
2H), 7.06 (d, J = 8.7 Hz, 2H); 13C NMR (CDCl3): d
156.96, 133.36, 131.10, 129.70, 117.42, 114.52, 75.52,
71.75, 68.71, 35.39, 10.54, 2.90; MS m/z: 232 (M+).
Anal. Calcd for C15H20O2: C, 77.55; H, 8.68. Found:
C, 77.83; H, 8.90.
To a stirred solution of compound 4 (12 g, 0.045 mol) in
dry hexane (50 ml), diethyl zinc (1.1 M solution in hex-
ane, 185 ml) was added at 0 ꢁC under N2 followed by
diiodomethane (18 ml, 0.224 mol). The reaction mixture
was stirred at 0 ꢁC for 6 h and poured over cold aqueous
solution of ammonium chloride. The organic layer was
separated and the aqueous layer was extracted repeat-
edly with diethyl ether. The combined organic layer
was washed with aq solution of sodium thiosulfate,
dried over Na2SO4, evaporated and the residue was
purified by column chromatography (silica gel, pet.
ether/EtOAc = 99/1) to afford compound 5 (12 g,
95%). IR (Neat): m 3065, 2931, 2859, 1611, 1583, 1511,
1454, 1380, 1336, 1240, 1176, 1096, 1020, 929,
4.7. 2-[4-(2-Cyclopropylmethoxy ethyl) phenoxymethyl]
oxirane 8
To an ice-cooled solution of allyloxy compound 7 (10 g,
0.043 mol) in dry CH2Cl2 (50 ml) meta-chloroperben-
zoic acid (11.48 g, 0.065 mol) was added in portions
for a period of 30 min. After the addition of mCPBA,
cooling was removed and continued stirring at room
temperature for 24 h. The reaction mixture was diluted
by adding dichloromethane (50 ml) and washed with
dilute 5% NaHCO3, followed by water. The organic layer
was dried over Na2SO4 and concentrated under reduced
pressure. The crude product was purified by column
chromatography (silica gel, pet. ether/EtOAc = 90/10)
to yield compound 8 (8 g, 75%). IR (Neat): m 3078,
3004, 2928, 2861, 1723, 1612, 1583, 1512, 1454, 1378,
829 cmÀ1 1H NMR (500 MHz, CDCl3): d 0.20 (m,
;
2H), 0.51 (m, 2H), 1.05 (m, 1H), 2.84 (t, J = 7.5 Hz,
2H), 3.27 (d, J = 7 Hz, 2H), 3.62 (t, J = 7.5 Hz, 2H),
5.04 (s, 2H), 6.89 (d, J = 8.6 Hz, 2H), 7.13 (d,
J = 8.6 Hz, 2H), 7.31 (t, J = 7.3 Hz, 1H), 7.37 (t,
J = 7.3 Hz, 2H), 7.42 (d, J = 7.3 Hz, 2H); 13C NMR
(CDCl3): d 157.24, 137.15, 131.36, 129.68, 128.36,
127.66, 127.24, 114.69, 75.35, 71.63, 69.92, 35.40,
10.53, 2.84; MS m/z: 282 (M+). Anal. Calcd for
C19H22O2: C, 80.82; H, 7.85. Found: C, 80.64; H, 7.55.
4.5. 4-(2-Cyclopropylmethoxy ethyl) phenol 6
1
1297, 1243, 1179, 1096, 1037, 937, 828 cmÀ1; H NMR
A solution of compound 5 (12 g, 0.062 mol) in methanol
(100 ml) was stirred over Raney-Nickel (10 ml slurry)
under H2 pressure (Parr Shaker; 65-psi pressure) for
5 h. The reaction mixture was filtered through a pad
of Celite and the filtrate was concentrated. The crude
product was purified by column chromatography (silica
gel, dichloromethane) to yield compound 6 (7 g, 86%).
IR (Neat): m 3329, 3081, 2934, 2864, 1614, 1595, 1516,
(200 MHz, CDCl3): d 0.20 (m, 2H), 0.54 (m, 2H), 1.06
(m, 1H), 2.70–2.75 (m, 1H), 2.83 (t, J = 7.3 Hz, 2H),
2.88–2.93 (m, 1H), 3.26 (d, J = 6.8 Hz, 2H), 3.28–3.36
(m, 1H), 3.61 (t, J = 7.3 Hz, 2H), 3.95 (dd, J = 11.1,
5.5 Hz, 1H), 4.15 (dd, J = 11.1, 3.2 Hz, 1H), 6.87 (d,
J = 8.2 Hz, 2H), 7.16 (d, J = 8.2, 2H); 13C NMR
(CDCl3): d 156.84, 131.53, 129.76, 114.42, 75.50, 71.63,
68.65, 50.09, 44.59, 35.32, 10.48, 2.88; MS m/z: 248
(M+). Anal. Calcd for C15H20O3: C, 72.55; H, 8.12.
Found: C, 72.70; H, 8.42.
1
1447, 1379, 1265, 1230, 1083, 930, 829 cmÀ1; H NMR
(500 MHz, CDCl3): d 0.21 (m, 2H), 0.54 (m, 2H), 1.05
(m, 1H), 2.83 (t, J = 7.3 Hz, 2H), 3.31 (d, J = 7 Hz,
2H), 3.64 (t, J = 7.3 Hz, 2H), 6.75 (d, J = 8.6, 2H),
7.06 (d, J = 8.6 Hz, 2H); 13C NMR (CDCl3): d 154.31,
130.27, 129.85, 115.26, 75.72, 71.84, 35.20, 10.44, 3.06;
MS m/z: 192 (M+). Anal. Calcd for C12H16O2: C,
74.97; H, 8.39. Found: C, 74.99; H, 8.54.
4.8. (S)-2 [4-(2-Cyclopropylmethoxy ethyl) phenoxy-
methyl] oxirane 9
A mixture of racemic epoxide 8 (10 g, 0.04 mol) and
(R,R)
salen
Co(III)OAc
complex-A
(0.130 g,
0.00022 mol) were vigorously stirred for 15 min. Then
cooled to 0 ꢁC, and added water (0.4 ml, 0.022 mol) over
a period of 1 h, through syringe. The reaction mixture
was stirred at room temperature and monitored by
HPLC (SS Wakosil-column) UV: 225 nm, 90% MeOH
in H2O. The reaction mixture was diluted with EtOAc,
dried over Na2SO4 and evaporated under reduced pres-
sure. The residue was purified by column chromatogra-
phy (silica gel, pet. ether/EtOAc = 70/30). The less polar
epoxide 9 eluted first as colourless liquid, [a]D = +2.05
(c 1, CHCl3); ee >99% [chiral HPLC analysis; DAICEL
CHIRALCEL OD (0.46 · 25 cm) column; eluent: hex-
ane/isopropanol = 97.5/2.5; flow rate: 1.0 ml/min;
detector: 254 nm (tR = 9.25 min), (tS = 10.25 min)]; fol-
lowed by the diol 10, ee 92% [chiral HPLC analysis;
DAICEL CHIRALCEL OD (0.46 · 25 cm) column;
eluent: hexane/isopropanol = 97.5/2.5; flow rate:
4.6. 1-Allyloxy-4-(2-cyclopropylmethoxy ethyl) benzene 7
To a solution of 4-(2-cyclopropylmethoxyethyl) phenol
6 (10 g, 0.052 mol) in tetrahydrofuran (65 ml) were suc-
cessively added potassium hydroxide (3.8 g, 0.067 mol)
and catalytic amount tetra butyl ammonium bromide
(0.15 g) and the reaction mixture was stirred at room
temperature under N2 for 1.5 h. Allyl bromide (6.8 ml,
0.078 mol) was added dropwise to the reaction mixture
and continued the stirring for 6 h. Filtered the solid,
washed the solid with THF and concentrated the filtrate
under reduced pressure. The residue was diluted with
EtOAc, washed with water, dried over Na2SO4 and
evaporated to obtain crude product, which was purified
by column chromatography (silica gel, pet. ether/
EtOAc = 90/10) to yield compound 7 (11.5 g, 95%).