J. Wang et al. / Tetrahedron 69 (2013) 5780e5790
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a silica gel column using 97/3 hexanes/EtOAc (Rf¼0.30 in 97% hexanes/
3% ethyl acetate). The product 1-OPiv was obtained as white solid
(537 mg, 74% yield); mp¼62.5 ꢀC. [Note: the product was further
recrystallized using petroleum ether prior to using it for catalysis.] 1H
to stir at room temperature for 15 h. The reaction mixture was then
diluted with 20 mL H2O and 20 mL CH2Cl2 and transferred to
a separatory funnel. The aqueous and organic layers were separated
and the organic layer was extracted with brine (1ꢁ20 mL). The
organic layer was dried over MgSO4, filtered, concentrated, and
chromatographed on a silica gel column using 95/5 hexanes/EtOAc
(Rf¼0.16 in 95% hexanes/5% ethyl acetate). The product 1-OCO(p-
OMeC6H4) was obtained as white solid (667 mg, 78% yield);
NMR (CDCl3):
7.09e7.04 (multiple peaks, 2H), 6.97e6.93 (multiple peaks, 2H), 1.22 (s,
9H). 13C{1H} NMR (CDCl3):
176.4, 157.3, 147.8, 142.7, 129.5, 126.7, 124.3,
d
7.30 (t, J¼8.0 Hz, 2H), 7.23e7.14 (multiple peaks, 3H),
d
123.7,122.8,121.1,117.4, 39.0, 27.0. IR (neat): 2971,1749,1586,1490,1479,
1459, 1253, 1205, 1182, 1112, 1068, 881, 796, 742, 692 cmꢂ1. HRMS calcd
for C17H18O3Na 293.1154; found: 293.1139.
mp¼81e82 ꢀC. 1H NMR (CDCl3):
d
7.99 (d, J¼8.8 Hz, 2H), 7.32e7.18
(multiple peaks, 5H), 7.10e7.04 (multiple peaks, 2H), 7.00 (d,
J¼8.6 Hz, 2H), 6.91 (d, J¼8.8 Hz, 2H), 3.87 (s, 3H). 13C{1H} NMR
4.4.2. A solution of alcohol 1-OH8i,19b (500 mg, 2.69 mmol,
1.0 equiv) in THF (7.0 mL) was added dropwise to a solution of
NaH (77.3 mg, 3.22 mmol, 1.2 equiv) in THF (1.8 mL) at 0 ꢀC. The
resulting mixture was allowed to stir at room temperature for
10 min after which a solution of N,N-diethyl carbamoyl chloride
(437 mg, 3.22 mmol, 1.2 equiv) in THF (2.9 mL) was added to it at
(CDCl3): d 164.2, 163.8, 157.3, 148.5, 142.3, 132.3, 129.5, 126.8, 124.1,
124.0, 123.1, 121.4, 120.7, 118.1, 113.6, 55.4. IR (neat): 3066, 3019,
2975, 2844, 1727, 1602, 1586, 1576, 1508, 1487, 1269, 1248, 1206,
1164, 1103, 1058, 1021, 880, 854, 786, 752, 691 cmꢂ1. HRMS calcd for
C20H16O4Naþ 343.0946; found: 343.0929.
0
ꢀC. The resulting solution was allowed to warm to room tem-
4.4.5. Alcohol 1-OH8i,19a (500 mg, 2.69 mmol, 1.0 equiv) and DMAP
(32.8 mg, 0.27 mmol, 0.1 equiv) were added to a schlenk flask,
which was then put under N2 atmosphere using a manifold. CH2Cl2
(9.3 mL), Et3N (326 mg, 3.22 mmol, 1.2 equiv), and 4-
trifluoromethylbenzoyl chloride (672 mg, 3.22 mmol, 1.2 equiv)
were added to the flask sequentially. The resulting mixture was
allowed to stir at room temperature for 15 h. The reaction mixture
was then diluted with 20 mL H2O and 20 mL CH2Cl2 and transferred
to a separatory funnel. The aqueous and organic layers were sep-
arated and the organic layer was extracted with brine (1ꢁ20 mL).
The organic layer was dried over MgSO4, filtered, concentrated, and
chromatographed on a silica gel column using 96/4 hexanes/EtOAc
(Rf¼0.26 in 96% hexanes/4% ethyl acetate). The product 1-OCO(p-
CF3C6H4) was obtained as a clear viscous oil (402 mg, 42% yield). 1H
perature and stirred at room temperature for 15 h. The reaction
mixture was then quenched with H2O (1.0 mL) at 0 ꢀC and
transferred to a separatory funnel. The aqueous and organic layers
were separated and the organic layer was extracted with 1.0 M
aqueous KOH solution (1ꢁ20 mL), H2O (1ꢁ20 mL), and brine
(1ꢁ20 mL). The organic layer was dried over MgSO4, filtered,
concentrated, and chromatographed on a silica gel column using
90/10 hexanes/EtOAc (Rf¼0.24 in 90% hexanes/10% ethyl acetate).
The product 1-OCONEt2 was obtained as a clear viscous oil
(471 mg, 61% yield). 1H NMR (CDCl3):
d 7.32e7.26 (multiple peaks,
3H), 7.21e7.14 (multiple peaks, 2H), 7.08e7.03 (multiple peaks,
2H), 6.98 (d, J¼8.1 Hz, 2H), 3.30 (q, J¼7.2 Hz, 2H), 3.19 (q,
J¼7.2 Hz, 2H), 1.11 (t, J¼7.2 Hz, 3H), 1.06 (t, J¼7.2 Hz, 3H). 13C{1H}
NMR (CDCl3):
d
157.6, 153.4, 147.9, 143.1, 129.4, 126.1, 124.3, 124.2,
NMR (CDCl3):
d
8.15 (d, J¼8.1 Hz, 2H), 7.71 (d, J¼8.2 Hz, 2H),
122.6, 121.2, 117.3, 42.2, 41.7, 13.8, 13.2. IR (neat): 2975, 1717, 1587,
1488, 1472, 1417, 1254, 1204, 1184, 1104, 1074, 879, 783, 745,
7.34e7.20 (multiple peaks, 5H), 7.12e7.06 (multiple peaks, 2H), 7.00
(d, J¼8.8 Hz, 2H). 13C{1H} NMR (CDCl3):
d 163.3, 157.0, 148.4, 141.8,
690 cmꢂ1
308.1271.
.
HRMS calcd for C17H19O3NNaþ 308.1263; found:
134.9 (2JCeF¼32 Hz), 132.3, 130.6, 129.7, 127.3, 125.4 (3JCeF¼3.4 Hz),
124.2, 123.6, 123.5 (3JCeF¼271 Hz), 123.4, 120.7, 118.1. IR (neat):
3069, 1745, 1587, 1488, 1411, 1323, 1254, 1203,1175, 1127, 1104, 1069,
1016, 881, 860, 768, 746, 689 cmꢂ1. HRMS calcd for C20H13O3F3Naþ
381.0714; found: 381.0709.
4.4.3. Alcohol 1-OH8i,19b (500 mg, 2.69 mmol, 1.0 equiv) and
DMAP (32.8 mg, 0.27 mmol, 0.1 equiv) were added to a schlenk
flask, which was then put under N2 atmosphere using a manifold.
CH2Cl2 (9.2 mL), Et3N (326 mg, 3.22 mmol, 1.2 equiv), and benzoyl
chloride (453 mg, 3.22 mmol, 1.2 equiv) were added to the flask
sequentially. The resulting mixture was allowed to stir at room
temperature for 12 h. The reaction mixture was then diluted with
20 mL H2O and 20 mL CH2Cl2 and transferred to a separatory
funnel. The aqueous and organic layers were separated and the
organic layer was extracted with brine (1ꢁ20 mL). The organic
layer was dried over MgSO4, filtered, concentrated, and chroma-
tographed on a silica gel column using 97/3 hexanes/EtOAc
(Rf¼0.26 in 97% hexanes/3% ethyl acetate). The product 1-OBz was
obtained as a clear viscous oil (380 mg, 49% yield). 1H NMR
4.4.6. 2-(p-Tolyloxy)phenyl pivalate (2-OPiv). 2-(p-Tolyloxy)phenol
(2-OH)8i,19a (500 mg, 2.50 mmol, 1.0 equiv) and DMAP (30.5 mg,
0.25 mmol, 0.1 equiv) were added to a schlenk flask, which was
then put under N2 atmosphere using a manifold. CH2Cl2 (8.6 mL),
Et3N (303 mg, 3.00 mmol, 1.2 equiv), and pivaloyl chloride (361 mg,
3.00 mmol, 1.2 equiv) were added to the flask sequentially. The
resulting mixture was allowed to stir at room temperature for 15 h.
The reaction mixture was then diluted with 20 mL H2O and 20 mL
CH2Cl2 and transferred to a separatory funnel. The aqueous and
organic layers were separated and the organic layer was extracted
with H2O (1ꢁ20 mL) and satd aq NH4Cl (1ꢁ20 mL). The organic
layer was dried over MgSO4, filtered, concentrated, and chroma-
tographed on a silica gel column using 97/3 hexanes/EtOAc
(Rf¼0.24 in 97% hexanes/3% ethyl acetate). The product 2-OPiv was
obtained as white solid (537 mg, 76% yield); mp¼73e74 ꢀC. 1H NMR
(CDCl3):
d
8.06 (d, J¼8.1 Hz, 2H), 7.60 (t, J¼7.5 Hz, 1H), 7.45 (t,
J¼7.8 Hz, 2H), 7.34e7.19 (multiple peaks, 5H), 7.11e7.06 (multiple
peaks, 2H), 7.02 (d, J¼8.4 Hz, 2H). 13C{1H} NMR (CDCl3):
d 164.5,
157.2, 148.5, 142.1, 133.4, 130.2, 129.6, 129.1, 128.4, 126.9, 124.1,
123.8, 123.2, 120.6, 118.2. IR (neat): 3065, 1740, 1586, 1487, 1451,
1249, 1202, 1173, 1103, 1077, 1057, 1023, 880, 794, 748, 703,
(CDCl3):
d
7.20e7.11 (multiple peaks, 5H), 7.00 (d, J¼7.8 Hz,1H), 6.88
(d, J¼8.2 Hz, 2H), 2.33 (s, 3H), 1.27 (s, 9H). 13C{1H} NMR (CDCl3):
690 cmꢂ1
313.0837.
.
HRMS calcd for C19H14O3Naþ 313.0841; found:
d 176.4, 154.9, 148.5, 142.4, 132.5, 130.0, 126.6, 123.8, 123.6, 120.3,
117.8, 39.0, 27.0, 20.6. IR (neat): 3038, 1751, 1593, 1505, 1491, 1457,
1253, 1208, 1177, 1164, 1113, 1103, 1034, 1014, 883, 835, 756,
741 cmꢂ1. HRMS calcd for C18H20O3Naþ 307.1310; found: 307.1305.
4.4.4. Alcohol 1-OH8i,19a (500 mg, 2.69 mmol, 1.0 equiv) and DMAP
(32.8 mg, 0.27 mmol, 0.1 equiv) were added to a schlenk flask,
which was then put under N2 atmosphere using a manifold. CH2Cl2
(9.3 mL), Et3N (326 mg, 3.22 mmol, 1.2 equiv), and 4-
methoxybenzoyl chloride (550 mg, 3.22 mmol, 1.2 equiv) were
added to the flask sequentially. The resulting mixture was allowed
4.4.7. 2-(4-Methoxyphenoxy)phenyl pivalate (3-OPiv). 2-(4-Methoxy-
phenoxy)phenol (3-OH)8i,19a (348 mg, 1.61 mmol, 1.0 equiv) and
DMAP (19.7 mg, 0.16 mmol, 0.1 equiv) were added to a schlenk flask,
which was then put under N2 atmosphere using a manifold. CH2Cl2