1161
S. Zhao et al.
Paper
Synthesis
1H NMR (400 MHz, CDCl3): δ = 7.45–7.30 (m, 5 H), 5.06 (dd, J = 7.8, 5.8
Hz, 1 H), 4.02 (ddd, J = 18.0, 12.2, 6.8 Hz, 2 H), 2.26 (br s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 134.84, 128.51, 127.69, 125.24, 77.48,
71.89, 28.81.
13C NMR (100 MHz, CDCl3): δ = 138.27, 128.92, 128.86, 127.90, 67.48,
HRMS (ESI): m/z [M + Na]+ calcd for C18H18Br2Cl2O2 + Na: 516.89428;
56.89.
found: 516.89459.
2-Bromo-2-(4-chlorophenyl)ethanol31
[CAS Reg. No. 1310696-03-7]
(2R,3R)-2,3-Bis(4′-bromobenzyloxy)-1,4-dibromobutane (11d)
Yield: 391 mg (67%); colorless oil; [α]D20 +16 (c 1.00, CHCl3).
FTIR (film): 2961, 2926, 2869, 1592, 1258, 1092, 1070, 925, 788, 683,
Yield: 212 mg (90%); colorless oil.
1H NMR (400 MHz, CDCl3): δ = 7.41–7.33 (m, 4 H), 5.03 (dd, J = 7.5, 5.9
Hz, 1 H), 4.00 (ddd, J = 18.1, 12.2, 6.7 Hz, 2 H), 2.39 (br s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 136.90, 134.68, 129.27, 129.02, 67.29,
55.49.
520 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.51–7.45 (m, 4 H), 7.21 (d, J = 8.4 Hz, 4
H), 4.68 (d, J = 11.6 Hz, 2 H), 4.55 (d, J = 11.6 Hz, 2 H), 3.95 (t, J = 5.0
Hz, 2 H), 3.54 (dd, J = 10.3, 6.8 Hz, 2 H), 3.45 (dd, J = 10.4, 4.8 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 135.33, 130.61, 128.74, 121.06, 77.53,
71.88, 28.80.
Dibromination of Diols 9 to 1,4-Dibromo Compounds 11; General
Procedure
HRMS (ESI): m/z [M + Na]+ calcd for C18H18Br4O2 + Na: 604.79325;
found: 608.78747.
NBS (534 mg, 3 mmol) was dissolved in CH2Cl2 (10 mL) contained in a
50 mL flask. Ph3P (786 mg, 3 mmol) and 9 (1 mmol) were added se-
quentially dropwise into the NBS solution at –78 °C. The reaction
mixture was stirred in the dark at r.t. for 12 h and the progression of
the reaction was monitored by TLC (eluent: PE–EtOAc, 20:1). The
mixture was then concentrated in vacuo and the product 11 was iso-
lated by flash chromatography on a silica gel column (eluent: PE–
EtOAc, 30:1).
(2R,3R)-2,3-Bis(4′-fluorobenzyloxy)-1,4-dibromobutane (11e)
Yield: 385 mg (83%); colorless oil; [α]D20 +16 (c 1.00, CHCl3).
FTIR (film): 2921, 2871, 1510, 1224, 1071, 1016, 824, 667, 551 cm–1
1H NMR (400 MHz, CDCl3): δ = 7.32 (dd, J = 8.5, 5.5 Hz, 4 H), 7.03 (t, J =
8.7 Hz, 4 H), 4.69 (d, J = 11.3 Hz, 2 H), 4.56 (d, J = 11.3 Hz, 2 H), 3.95 (t,
J = 5.2 Hz, 2 H), 3.53 (dd, J = 10.2, 7.1 Hz, 2 H), 3.44 (dd, J = 10.3, 4.8 Hz,
2 H).
13C NMR (100 MHz, CDCl3): δ = 163.02, 160.57, 132.35, 129.27,
114.71, 114.50, 77.43, 72.13, 28.99.
HRMS (ESI): m/z [M + Na]+ calcd for C18H18Br2F2O2 + Na: 484.95338;
found: 484.95390.
.
(2R,3R)-2,3-Dibenzyloxy-1,4-dibromobutane (11a)32
[CAS Reg. No. 113321-60-1]
Yield: 358 mg (90%); colorless oil; [α]D20 +10 (c 1.00, CHCl3).
1H NMR (400 MHz, CDCl3): δ = 7.43–7.26 (m, 10 H), 4.72 (d, J = 11.4
Hz, 2 H), 4.60 (d, J = 11.4 Hz, 2 H), 3.96 (t, J = 5.2 Hz, 2 H), 3.55 (dd, J =
10.1, 7.0 Hz, 2 H), 3.44 (dd, J = 10.2, 4.8 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 136.57, 127.63, 127.40, 127.23, 77.51,
72.85, 29.17.
HRMS (ESI): m/z [M + NH4]+ calcd for C18H24Br2NO2: 444.01683;
found: 444.01823.
(2R,3R)-2,3-Bis(3′-fluorobenzyloxy)-1,4-dibromobutane (11f)
Yield: 394 mg (85%); colorless oil; [α]D20 +16 (c 1.00, CHCl3).
FTIR (film): 2926, 2870, 1592, 1257, 1090, 1069, 925, 785, 683, 521
cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.31 (td, J = 7.9, 5.9 Hz, 2 H), 7.21–7.04
(m, 4 H), 7.00 (td, J = 8.4, 2.2 Hz, 2 H), 4.73 (d, J = 11.7 Hz, 2 H), 4.60 (d,
J = 11.7 Hz, 2 H), 4.06–3.91 (m, 2 H), 3.57 (dd, J = 10.3, 6.9 Hz, 2 H),
3.47 (dd, J = 10.4, 4.8 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 163.09, 160.64, 138.92, 129.05,
122.50, 113.94, 77.63, 71.91, 28.80.
(2R,3R)-2,3-Bis(4′-methylbenzyloxy)-1,4-dibromobutane (11b)
Yield: 319 mg (70%); colorless oil; [α]D20 +12 (c 1.00, CHCl3).
FTIR (film): 2924, 2865, 1455, 1259, 1220, 1071, 1021, 925, 803, 683,
523 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.28–7.20 (m, 4 H), 7.15 (d, J = 7.8 Hz, 4
H), 4.67 (d, J = 11.3 Hz, 2 H), 4.56 (d, J = 11.3 Hz, 2 H), 3.94 (t, J = 5.4
Hz, 2 H), 3.52 (dd, J = 10.0, 7.1 Hz, 2 H), 3.41 (dd, J = 10.2, 4.8 Hz, 2 H),
2.34 (s, 6 H).
13C NMR (100MHz, CDCl3): δ = 136.85, 133.43, 128.16, 127.38, 77.14,
72.57, 29.15, 20.19.
HRMS (ESI): m/z [M + Na]+ calcd for C18H18Br2F2O2 + Na: 484.95338;
found: 484.95394.
(2R,3R)-2,3-Bis(2′-fluorobenzyloxy)-1,4-dibromobutane (11g)
Yield: 417 mg (90%); colorless oil; [α]D20 +12 (c 1.00, CHCl3).
FTIR (film): 2925, 1492, 1456, 1231, 1072, 942, 758, 667, 529 cm–1
1H NMR (400 MHz, CDCl3): δ = 7.34 (td, J = 7.4, 1.6 Hz, 2 H), 7.23 (tdd,
J = 7.4, 5.4, 1.8 Hz, 2 H), 7.06 (td, J = 7.5, 1.0 Hz, 2 H), 7.03–6.90 (m, 2
H), 4.71 (d, J = 11.6 Hz, 2 H), 4.61 (d, J = 11.6 Hz, 2 H), 3.98–3.86 (m, 2
H), 3.50 (dd, J = 10.2, 7.3 Hz, 2 H), 3.42 (dd, J = 10.3, 5.0 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 158.85, 129.96, 129.17, 123.33,
114.65, 114.44, 104.11, 77.50, 66.17, 28.66.
HRMS (ESI): m/z [M + Na]+ calcd for C18H18Br2F2O2 + Na: 484.95338;
found: 484.95383.
.
HRMS (ESI): m/z [M + Na]+ calcd for C20H24Br2O2 + Na: 477.00353;
found: 477.00346.
(2R,3R)-2,3-Bis(4′-chlorobenzyloxy)-1,4-dibromobutane (11c)
Yield: 357 mg (72%); colorless oil; [α]D20 +16 (c 1.00, CHCl3).
FTIR (film): 2961, 2928, 2870, 1511, 1263, 1224, 1089, 1016, 810,
684, 542 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.31–7.26 (m, 8 H), 4.69 (d, J = 11.6 Hz,
2 H), 4.56 (d, J = 11.6 Hz, 2 H), 3.95 (t, J = 5.1 Hz, 2 H), 3.72 (dd, J = 14.1,
7.0 Hz, 2 H), 3.54 (dd, J = 10.3, 6.9 Hz, 2 H), 3.45 (dd, J = 10.3, 4.8 Hz, 2
H).
(2R,3R)-2,3-Diallyloxy-1,4-dibromobutane (11h)
Yield: 295 mg (90%); colorless oil; [α]D20 +16 (c 1.00, CHCl3).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, 1154–1162