Synlett 2008(6): 853-856  
DOI: 10.1055/s-2008-1042902
LETTER
© Georg Thieme Verlag Stuttgart · New York

Direct and Facile Bromination at the 5- and 5′-Positions of (R)-6,6′-Dialkyl- and (R)-6,6′-Diaryl-2,2′-Binaphthols

Shuwei Zhang, Yan Liu, Hui Huang, Lifei Zheng, Linglin Wu, Yixiang Cheng*
School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. of China
Fax: +86(25)83317761; e-Mail: yxcheng@nju.edu.cn;
Further Information

Publication History

Received 5 October 2007
Publication Date:
11 March 2008 (online)

Abstract

(R)-5,5′-Dibromo-6,6′-dibutyl-2,2′-binaphthol, (R)-5,5′-dibromo-6,6′-di(4-methylphenyl)-2,2′-binaphthol, (R)-5,5′-dibromo-6,6′-di(3,5-dimethylphenyl)-2,2′-binaphthol, and (R)-5,5′-dibromo-6,6′-di(4-trifluoromethylphenyl)-2,2′-binaphthol were synthesized from (R)-1,1′-bi-2-naphthol by a five-step reaction in excellent yields under mild conditions.

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General Procedure for Suzuki Reaction Method and Hydrolysis Reaction Method
(R)-6,6′-Dibromo-2,2′-bis(methoxymethoxy)-1,1′ -binaphthyl (1 equiv) is stirred with the corresponding boronic acid (2.5-3.5 equiv) and Pd(PPh3)4 (7-10 mol%) in a mixture solution of THF or DME and 2 M K2CO3 solution (referred to as solvent/base) overnight. The mixture was filtered through a short column of silica gel with EtOAc as an eluent. After removal of solvents under reduced pressure, the residue was extracted with CH2Cl2. The organic layer was washed with H2O and brine, dried over anhyd Na2SO4 and concentrated. The crude product was purified by column chromatography on silica gel. The product was dissolved in THF. A mixture of MeOH and HCl (12 M) was added and stirred at r.t. for 12 h. The solvent was removed under reduced pressure, and the residue was extracted with EtOAc. The organic layer was washed with 2 M NaHCO3 solution and brine twice, dried over anhyd Na2SO4, and concentrated. The crude product was purified by column chromatography on silica gel.
General Procedure for Brominated Reaction Method A solution of Br2 (5 equiv in CH2Cl2) was slowly added to a solution of (R)-6,6′-diaryl-2,2′-binaphthol in CH2Cl2 at -15 °C or 0 °C over 1 h. The solution was stirred overnight and gradually warmed to r.t. The reaction was quenched with sat. NaHSO3 solution and extracted with CH2Cl2. The combined organic layers were washed with H2O and brine twice, and then dried over anhyd Na2SO4. After removal of solvent, the crude product was purified by column chromatography on silica gel
( R )-6,6′-Dibutyl-2,2′-binaphthol White solid (0.71 g, 93% yield); mp 72-74 °C. [α]D -82.9 (c 0.31, CH2Cl2). 1H NMR (300 MHz, CDCl3): δ = 7.92 (d, 2 H, J = 9.0 Hz), 7.69 (s, 2 H), 7.36 (d, 2 H, J = 9.0 Hz), 7.19 (dd, 2 H, J = 8.4 Hz), 7.12 (d, 2 H, J = 8.4 Hz), 5.01 (s, 2 H), 2.76 (t, 4 H, J = 7.8 Hz), 1.74-1.64 (m, 4 H), 1.49-1.36 (m, 4 H), 0.97 (t, 6 H, J = 7.2 Hz). 13C NMR (75 MHz, CDCl3): δ = 152.5, 139.0, 132.1, 131.2, 130.0, 129.4, 127.3, 124.6, 118.0, 111.3, 35.9, 33.9, 22.8, 14.4. FT-IR (KBr): 3503.4, 3421.9, 2950.1, 2921.8, 1598.1, 1507.3, 1474.1, 1363.7, 1214.1, 1142.6, 1124.5, 952.2, 880.6, 827.1, 684.0, 555.6 cm-1.
( R )-6,6′-Di-(4-methylphenyl)-2,2′-binaphthol White solid (0.57 g, 93% yield); mp 113-116 °C; [α]D
-288.2 (c 0.5, CH2Cl2). 1H NMR (300 MHz, CDCl3): δ = 8.08 (s, 2 H), 8.03 (d, 2 H, J = 8.9 Hz), 7.57 (d, 6 H, J = 8.0 Hz), 7.41 (d, 2 H, J = 8.9 Hz), 7.26-7.24 (m, 6 H), 5.12 (s, 2 H), 2.40 (s, 6 H). 13C NMR (75 MHz, CDCl3): δ = 153.1, 138.3, 137.5, 137.3, 132.8, 132.1, 130.2, 130.0, 127.6, 127.5, 126.4, 125.1, 118.6, 111.1, 21.6. FT-IR (KBr): 3500.3, 3021.4, 2918.2, 1621.8, 1596.9, 1568.6, 1518.3, 1500.6, 1383.5, 1355.9, 1286.5, 1217.5, 1189.3, 1173.4, 1148.6, 1128.3, 935.3, 889.5, 812.5, 757.4, 525.4 cm-1.
( R )-6,6′-Di-(3,5-dimethylphenyl)-2,2′-binaphthol White solid (1.07 g, 99% yield); mp 107-109 °C; [α]D
-171.4 (c 0.1, CH2Cl2). 1H NMR (300 MHz, CDCl3): δ = 8.11 (s, 2 H), 8.06 (d, 2 H, J = 9.0 Hz), 7.60 (d, 2 H, J = 8.4 Hz), 7.45 (d, 2 H, J = 8.7 Hz), 7.32 (s, 4 H), 7.28 (d, 2 H, J = 9.0 Hz), 7.05 (s, 2 H), 5.16 (s, 2 H), 2.43 (s, 12 H). 13C NMR (75 MHz, CDCl3): δ = 153.1, 141.2, 138.8, 137.6, 132.9, 132.1, 130.1, 129.4, 127.7, 126.7, 125.6, 125.1, 118.6, 111.2, 21.9. FT-IR (KBr): 3522.3, 3419.5, 3014.8, 2955.4, 2913.5, 1621.9, 1593.6, 1504.3, 1481.1, 1383.8, 1355.2, 1216.7, 1147.1, 1128.7, 945.0, 850.2, 824.1, 683.9, 572.9 cm-1.
( R )-6,6′-Di-(4-trifluoromethylphenyl)-2,2′-binaphthol
White solid (1.25 g, 95% yield); mp 209-210 °C; [α]D -225.2 (c 0.5, CH2Cl2). 1H NMR (CDCl3): δ = 8.16 (d, 2 H, J = 1.5 Hz), 8.10 (d, 2 H, J = 9.0 Hz), 7.80 (d, 4 H, J = 8.7 Hz), 7.74 (d, 4 H, J = 8.4 Hz), 7.60 (dd, 2 H, J = 8.7 Hz), 7.49 (d, 2 H, J = 9.0 Hz), 7.31 (d, 2 H, J = 8.7 Hz), 5.17 (s, 2 H). 13C NMR (CDCl3): δ = 153.3, 144.3, 135.5, 133.1, 132.0, 129.7, 129.2, 127.5, 127.0, 126.9, 126.0, 125.9, 125.8, 118.6, 110.8. FT-IR (KBr): 3521.3, 3492.1, 3413.8, 1616.2, 1599.0, 1502.0, 1472.1, 1409.8, 1385.0, 1326.8, 1290.8, 1166.8, 1124.0, 1109.7, 1068.5, 1014.7, 849.2, 820.4, 778.3, 611.3 cm-1.
Compound ( R )-1
Bromine (0.14 mL, 2.8 mmol in 5 mL CH2Cl2) was slowly added to a solution of (R)-6,6′-dibutyl-2,2′-binaphthol (0.52 g, 1.33 mmol) in CH2Cl2 (10 mL) at -78 °C over 1 h. The solution was stirred overnight and gradually warmed to r.t. After removal of solvent, a white solid product (R)-1 can directly be obtained in the yield of 99% (0.73 g) without further purification; mp 48-50 °C; [α]D -13.3 (c 0.23, CH2Cl2). 1H NMR (300 MHz, CDCl3): δ = 8.52 (d, 2 H, J = 9.0 Hz), 7.46 (d, 2 H, J = 9.6 Hz), 7.17 (d, 2 H, J = 8.4 Hz), 7.01 (d, 2 H, J = 8.7 Hz), 5.04 (s, 2 H), 2.93-2.92 (m, 4 H), 1.67-1.62 (m, 4 H), 1.49-1.42 (m, 4 H), 0.99-0.94 (m, 6 H). 13C NMR (75 MHz, CDCl3): δ = 153.1, 139.1, 133.4, 131.5, 130.2, 128.9, 124.6, 124.0, 119.2, 111.3, 37.3, 32.7, 23.0, 14.3. ESI-MS: m/z = 554.4 [M + 1]. Anal. Calcd for C28H28Br2O2: C, 60.45; H, 5.07. Found: C, 60.41; H, 5.11.
FT-IR (KBr): 3530.2, 3027.4, 2956.5, 2928.9, 1597.9, 1567.3, 1467.1, 1367.7, 1248.7, 1212.0, 1154.1, 1132.9, 970.7, 819.2, 709.0, 579.3 cm-1.
Compound ( R )-2
White solid (600 mg, 83% yield); mp >250 °C; [α]D -70.0 (c 0.5, CH2Cl2). 1H NMR (300 MHz, CDCl3): δ = 8.61 (d, 2 H, J = 9.3 Hz), 7.52 (d, 2 H, J = 9.3 Hz), 7.33 (d, 4 H, J = 8.1 Hz), 7.26 (d, 6 H, J = 7.2 Hz), 7.14 (d, 2 H, J = 8.7 Hz), 5.14 (s, 2 H), 2.42 (s, 6 H). 13C NMR (75 MHz, CDCl3): δ = 153.7, 139.6, 139.5, 137.8, 134.0, 132.3, 130.8, 129.9, 129.2, 128.9, 124.0, 123.7, 119.7, 111.3, 21.7. ESI-MS:
m/z = 623.5 [(M + 1]. Anal. Calcd for C34H24Br2O2: C, 65.41; H, 3.87. Found: C, 65.46; H, 3.77. FT-IR (KBr): 3525.8, 3497.6, 3024.1, 2917.2, 1611.0, 1592.1, 1564.1, 1517.5, 1487.4, 1466.4, 1366.7, 1231.9, 1209.8, 1173.8, 1152.2, 1132.1, 955.3, 817.7, 810.9, 759.6, 546.7 cm-1.
Compound ( R )-3 White solid (1.52 g, 77.1% yield); mp 184-186 °C; [α]D
-69.57 (c 0.1, CH2Cl2). 1H NMR (300 MHz, CDCl3): δ = 8.63 (d, 2 H, J = 9.3 Hz), 7.55 (d, 2 H, J = 9.0 Hz), 7.27 (d, 2 H, J = 7.8 Hz), 7.23 (s, 2 H), 7.16 (s, 6 H), 5.18 (s, 2 H), 2.49 (s, 12 H). 13C NMR (75 MHz, CDCl3): δ = 153.8, 140.8, 138.8, 138.4, 134.1, 132.4, 130.4, 129.7, 128.8, 127.5, 124.0, 123.5, 119.8, 111.3, 24.4. ESI-MS: m/z = 652.4 [M + 1]. Anal. Calcd for C28H28Br2O2: C, 66.27; H, 4.33. Found: C, 66.38; H, 4.21. FT-IR (KBr): 3520.2, 3029.7, 2951.2, 2920.7, 1600.1, 1566.2, 1473.2, 1369.0, 1305.5, 1208.9, 1151.7, 1134.2, 1027.9, 969.5, 820.3, 678.3, 567.5 cm-1. Compound ( R )-4
White solid (503 mg, 79% yield); mp 152-154 °C; [α]D -46.80 (c 0.5, CH2Cl2). 1H NMR (300 MHz, CDCl3): δ = 8.64 (d, 2 H, J = 9.3 Hz), 7.74 (d, 4 H, J = 8.1 Hz), 7.58 (d, 6 H, J = 9.0 Hz), 7.26 (d, 2 H, J = 9.6 Hz), 7.20 (d, 2 H, J = 8.7 Hz), 5.29 (s, 2 H). 13C NMR (CDCl3): δ = 153.7, 145.5, 137.8, 134.1, 131.9, 130.0, 129.6, 128.4, 126.0, 125.2, 124.0, 123.2, 122.4, 120.0, 111.3. ESI-MS: m/z 731.7 [M + 1]. Anal. Calcd for C28H28Br2O2: C, 55.76; H, 2.48. Found: C, 56.12; H, 2.50. FT-IR (KBr): 3522.1, 3391.9, 1702.3, 1616.2, 1598.3, 1471.8, 1370.3, 1324.6, 1165.3, 1124.9, 1107.5, 1081.3, 1060.4, 1018.0, 819.6, 781.3, 610.0 cm-1.