8
M. Mešková, M. Putala / Tetrahedron: Asymmetry xxx (2013) xxx–xxx
134.8, 133.9, 133.6, 133.2, 132.7, 132.4, 132.2, 131.3, 131.3, 128.6,
128.5, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.5, 127.3, 126.9,
126.8, 126.3, 125.8, 106.9, 100.8, 55.1; 31P NMR (121 MHz, CDCl3):
7.36 (m, 2H), 7.19–7.01 (m, 4H), 6.86 (d, J = 8.6 Hz, 1H), 6.65 (d,
J = 8.0 Hz, 1H), 6.15 (d, J = 8.2 Hz, 1H), 3.82 (s, 3H, OCH3), 2.42 (s,
3H, OCH3), 1.88–1.58 (m, 5H), 1.53–1.40 (m, 3H), 1.31–1.16 (m,
4H), 1.15–0.97 (m, 4H), 0.89–0.82 (m, 2H), 0.72 (t, J = 9.7 Hz, 2H),
0.35 (br s, 3H, BH3) ppm; 13C NMR (75 MHz, CDCl3): d = 158.2,
157.6, 142.1, 136.3, 134.9, 134.8, 134.1, 133.6, 132.7, 132.2,
130.4, 129.7, 128.7, 127.5, 127.3, 127.2, 126.6, 126.4, 126.0,
125.5, 125.4, 124.9, 124.8, 118.0, 104.2, 103.7, 55.3, 53.2, 31.4,
29.0, 28.9, 28.8, 27.3, 27.0, 26.7, 26.6, 26.4, 25.7, 25.5, 23.0 ppm;
31P NMR (121 MHz, CDCl3): d = 36.40 (s) ppm; IR (neat, cmꢀ1):
d = ꢀ14.96; IR (neat, cmꢀ1):
m = 3050 (ar C–H st), 2999, 2953 (OCH3
st), 2834 (OCH3 st), 1952, 1818, 1771 (ar C–C w), 1591, 1193 (as –
C–OCH3 st), 1152 (as –C–OCH3 st), 1064 (sy –C–OCH3 st), 1042 (sy –
C–OCH3 st), 906, 865, 816 (P–C st), 808 (P–C st); Elem. Anal. Calcd
for C39H29P (574.65): C, 83.60; H, 5.44. Found: C, 82.98; H, 5.53.
Enantiomeric excess was determined to be >99% ee by HPLC anal-
ysis (Chiralcel AD-H column, mobile phase: hexanes/i-PrOH = 95/5,
320 nm), temperature: 20 °C, flow: 0.5 ml/min, pressure: 20 bar.
m
= 2931 (ar C–H st), 2911, 2849 (OCH3 st), 2825 (OCH3 st), 2377
(B–H st), 2251, 2220, 1589 (ar C–C w), 1472, 1431, 1260 (as –C–
OCH3 st), 1249 (as –C–OCH3 st), 1106 (sy –C–OCH3 st), 1062 (sy –
C–OCH3 st), 1031, 823, 817, 756, 730 (P–C st), 701 (P–C st); Elem.
Anal. Calcd for C40H46BO2P (600.58): C, 79.99; H, 7.72. Found: C,
79.56; H, 7.78. Enantiomeric excess was determined to be >99%
ee by HPLC analysis (Chiralcel AD-H column, mobile phase: hex-
anes/i-PrOH = 98/2, 320 nm), temperature: 20 °C, flow: 0.5 ml/
min, pressure: 20 bar.
4.4.5. (R)-Dicyclohexyl[20-(2-methoxyphenyl)-1,10-binaphthal
ene-2-yl]phosphane–borane 1aBꢁBH3
Eluent hexanes/CHCl3 = 4/1; yield 205 mg (72%); mp 230–
232 °C; ½a 2D0
ꢃ
¼ þ14:0 (c 1, CHCl3); 1H NMR (600 MHz, CDCl3):
d = 8.01 (d, J = 8.6 Hz, 1H), 7.90 (d, J = 8.1 Hz, 2H), 7.86 (dd, J = 7.7,
5.5 Hz, 2H), 7.67 (d, J = 8.6 Hz, 1H), 7.51–7.45 (m, 1H), 7.41 (ddd,
J = 8.0, 6.8, 1.0 Hz, 1H), 7.24 (d, J = 3.6 Hz, 2H), 7.12 (ddd, J = 8.4,
6.8, 1.2 Hz, 1H), 7.06 (ddd, J = 7.8, 4.2, 0.6 Hz, 2H), 6.89–6.68 (m,
2H), 6.49 (br s, 1H), 3.55 (br s, 3H), 1.76–1.61 (m, 5H), 1.54–1.45
(m, 2H), 1.40–1.23 (m, 5H), 1.16–0.98 (m, 5H), 0.96–0.59 (m, 5H),
0.2 (br s, 3H, BH3); 13C NMR (150.8 MHz, CDCl3): d = 156.3 (C–O),
135.8, 135.2, 135.1, 134.4, 134.1, 133.4, 132.7, 131.5, 130.6,
129.7, 128.6, 128.5, 127.9, 127.6, 127.7, 127.6, 127.1, 126.9,
126.8, 126.4, 125.7, 125.6, 125.5, 119.9, 110.6, 54.4 (OCH3), 34.7,
32.5, 31.6, 28.4, 28.1, 27.6, 27.0, 26.9, 26.8, 25.7, 25.6, 25.3; 31P
NMR (242.8 MHz, CDCl3, 25 °C): d = 33.55 (br s); 31P NMR
4.5. Catalytic studies
General procedure: A round bottom flask equipped with a mag-
netic stirrer bar and a condenser was charged with solid materials:
boronic acid
7
(0.18 mmol), base (0.3 mmol), Pd(OAc)2
(0.005 mmol, 1.12 mg), and ligand (R)-1 (0.02 mmol), and then
purged three times under argon without any solvent. A solution
of bromide 8 or 10 (0.1 mmol) in solvent (1.25 ml) was injected
and this mixture was stirred for 72 h at reflux unless said other-
wise. After this time, the flask was allowed to warm to room tem-
perature, after which dichloromethane (5 ml) and water (5 ml)
were added to this mixture. The layers were separated and the
aqueous layer was extracted with dichloromethane (3 ꢂ 5 ml).
The combined organic layers were dried over anhydrous Na2SO4,
filtered, and the solvent evaporated under reduced pressure. The
crude mixture was purified by column chromatography over silica
gel, to give the corresponding products. Enantiomeric excesses
were determined by HPLC using Chiralcel OD-H, AD-H, or OJ-H
(Daicel Chemical Industries) column.
(242.8 MHz, CDCl3, 35 °C): d = 32.68 (s); IR (neat, cmꢀ1):
m = 3029
(ar C–H st), 2928, 2847 (OCH3 st), 2392 (B–H st), 1933, 1825 (ar
C–C w), 1497, 1446, 1243 (as –C–OCH3 st), 1018 (sy –C–OCH3 st),
821, 749 (P–C st), 691 (P–C st); Elem. Anal. Calcd for C39H44BOP
(570.55): C, 82.10; H, 7.77. Found: C, 81.78; H, 8.20. Enantiomeric
excess was determined to be >99% ee by HPLC analysis (Chiralcel
AD-H column, mobile phase: hexanes/i-PrOH = 98/2, 320 nm),
temperature: 20 °C, flow: 0.5 ml/min, pressure: 20 bar.
4.4.6. (R)-Dicyclohexyl[20-(2-methylphenyl)-1,10-binaphthalene-
2-yl]phosphane–borane 1bBꢁBH3
Eluent hexanes/CHCl3 = 4/1; yield 139 mg (50%); mp 155–
158 °C; ½a 2D0
ꢃ
¼ þ8:2 (c 1, CHCl3); 1H NMR (300 MHz, CDCl3):
4.5.1. 1-(2-Isopropoxyphenyl)-2-methylnaphthalene 6f
Eluent hexanes/CHCl3 = 4/1; colorless oil; 1H NMR (300 MHz,
CDCl3): d = 7.85–7.79 (m, 1H), 7.75 (d, J = 8.4 Hz, 1H), 7.44–7.33
(m, 4H), 7.33–7.25 (m, 1H), 7.16–7.01 (m, 3H), 4.35–4.20 (m,
1H), 2.23 (s, 3H, Me), 1.09–1.02 (d, J = 6.0 Hz, 3H), 0.94 (d,
J = 6.1 Hz, 3H); 13C NMR (75 MHz, CDCl3): d = 155.9, 135.0, 133.8,
133.0, 132.1, 132.0, 131.9, 129.9, 128.5, 128.4, 127.6, 126.9,
126.1, 125.4, 124.4, 120.7, 115.1, 70.6, 22.1, 20.6; MS (ESI) calcd
for C20H20O (276.37): 276.15; found 276.20.
d = 8.04 (d, J = 8.5 Hz, 1H), 8.00–7.64 (m, 4H), 7.64–7.32 (m, 3H),
7.31–7.06 (m, 4H), 7.02–6.78 (m, 2H), 6.75–6.37 (m, 2H), 2.53 (br
s, 3H, CH3), 1.98–1.67 (m, 5H), 1.64–1.46 (m, 5H), 1.22–1.03 (m,
5H), 0.99–0.68 (m, 5H), 0.30 (br s, 3H, BH3) ppm; 13C NMR
(75 MHz, CDCl3): d = 144.2, 139.8, 137.3, 136.2, 135.0, 134.5,
133.3, 132.4, 131.6, 129.9, 129.3, 129.0, 128.2, 128.1, 127.9,
127.8, 127.7, 127.3, 127.2, 127.1, 125.7, 125.5, 125.3, 124.7,
123.6, 106.0, 34.7, 34.5, 33.6, 31.6, 29.0, 28.2, 27.6, 27.0, 25.7,
25.3, 22.7, 22.1, 20.7 (CH3) ppm; 31P NMR (121 MHz, CDCl3):
d = 31.3 (major atropoisomer), 27.0 (minor atropoisomer) ppm;
4.5.2. 2-Methyl-1-(2-phenoxyphenyl)naphthalene 6g
IR (neat, cmꢀ1):
m
= 3052 (ar C–H st), 2960, 2850, 2372 (B–H st),
Eluent hexanes/CHCl3 = 4/1; white solid; mp 145–147 °C; 1H
NMR (300 MHz, CDCl3): d = 7.83–7.69 (m, 2H), 7.51–7.44 (m, 1H),
7.42–7.26 (m, 5H), 7.24–7.09 (m, 3H), 7.09–7.01 (m, 1H), 6.97–
6.89 (m, 1H), 6.82–6.74 (m, 2H), 2.28 (s, 3H, Me). 13C NMR
(75 MHz, CDCl3): d = 157.1, 155.7, 134.3, 133.9, 133.0, 132.7,
132.0, 130.8, 129.5, 129.3, 129.0, 128.6, 128.0, 127.6, 126.1,
125.9, 124.8, 123.4, 123.1, 119.3, 118.9, 118.7, 20.9; IR (neat,
1918, 1820 (ar C–C w), 1552, 1502, 1447 (as CH3 d), 1379 (sy CH3
d), 1089, 1173, 1006, 821, 746 (P–C st), 700 (P–C st); Elem. Anal.
Calcd for C39H44BP (554.55): C, 84.47; H, 8.00. Found: C, 84.00;
H, 8.42. Enantiomeric excess was determined to be >99% ee by
HPLC analysis (Chiralcel AD-H column, mobile phase: hexanes/i-
PrOH = 95/5, 320 nm), temperature: 20 °C, flow: 0.5 ml/min, pres-
sure: 20 bar.
cmꢀ1):
m = 3047 (ar C–H st), 2921, 2852, 1951, 1923 (ar C–C w),
1588, 1574, 1485, 1444, 1243 (as –C–OPh st), 1158 (sy –C–OPh
st), 1099; Elem. Anal. Calcd for C23H18O (310.14): C, 89.00; H,
5.85, O, 5.15. Found: C, 88.19; H, 6.20.
4.4.7. (R)-Dicyclohexyl[20-(2,6-dimethoxyphenyl)-1,10-binaphth-
alene-2-yl]phosphane–borane 1cBꢁBH3
Eluent hexanes/CHCl3 = 4/1; yield 114 mg (38%); mp 245–
246 °C; ½a 2D0
ꢃ
¼ þ17:75 (c 1, CHCl3); 1H NMR (300 MHz, CDCl3):
4.5.3. 1-(2-Isopropoxyphenyl)-2-methoxynaphthalene 9e
Eluent hexanes/ethyl acetate = 7/1; colorless oil; 1H NMR
(300 MHz, CDCl3): d = 7.91–7.77 (m, 2H), 7.44–7.27 (m, 5H),
d = 8.03 (d, J = 8.4 Hz, 1H), 7.98 (d, J = 8.7 Hz, 1H), 7.87 (d,
J = 8.0 Hz, 1H), 7.80 (d, J = 8.5 Hz, 2H), 7.55–7.47 (m, 1H), 7.45–