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solved in THF (307 mL) and cooled to 0 °C under argon. TBAF
(21.8 mL, 21.8 mmol) was then added dropwise at 0 °C. The reaction
[(Z)-7-Bromo-7-(4-bromo-3-methoxyphenyl)ethenyl]boronic
Acid (33): To a well-stirred solution of BBr3 (0.19 mL, 1.92 mmol) in
mixture was warmed to room temperature, then stirred at this tem- DCM (18 mL) was added 1-bromo-4-ethynyl-2-methoxybenzene 10
perature for 3 d. This mixture was then evaporated to give a dark
(0.402 g, 1.92 mmol) at –78 °C under a positive pressure of argon.
brown oil. The crude product was purified by silica gel chromatog-
The resulting purple solution was stirred at –78 °C for 2 h and
raphy, eluent 0–5 % EtOAc in hexane. Pure fractions were evapo- warmed to 0 °C before adding NaHCO3 (0.323 g, 3.84 mmol) dis-
rated to give the desired product as an orange solid (3.76 g, 86 %).
solved in H2O (13 mL). The resulting pale yellow solution was stirred
M.p. 37.4–38.8 °C. 1H NMR (400 MHz, CDCl3, 25 °C, TMS): δ = 3.12 for 25 min, then transferred to a separating funnel. The mixture was
3
(s, 1 H), 3.89 (s, 3 H), 6.92–7.01 (m, 2 H), 7.48 [d, J(H,H) = 8.1 Hz, 1
extracted with DCM (2 × 20 mL) and the organics washed with H2O
(20 mL) and brine (20 mL), dried with MgSO4, filtered and evapo-
rated to give the desired product as an unstable pale yellow solid
H] ppm. 13C NMR (176 MHz, CDCl3, 25 °C, TMS): δ = 56.2, 77.9, 82.8,
112.9, 115.2, 122.3, 125.5, 133.2, 155.6 ppm. IR (film): ν(inter alia) =
˜
2051 (w), 2939 (w), 3258 (s) cm–1. MS (ASAP) m/z 210.0 [M+], 212.0 (0.522 g, 81 %). M.p. 115.3–118.1 °C. 1H NMR (400 MHz, CDCl3, 25 °C,
[M+]. HRMS (ASAP) m/z calcd. for C9H7O79Br, 209.9680 [M+], found
TMS): δ = 3.94 (s, 3 H), 6.47 (s, 1 H), 7.03–7.19 (m, 2 H), 7.45–7.60
(m, 1 H) ppm. 11B NMR (128 MHz, CDCl3, 25 °C, TMS): δ = 27.6 ppm.
The compound was taken on to the next stage without any further
purification or characterisation.
209.9689.
(Z)-2-[2-Bromo-2-(4-bromo-3-methoxyphenyl)vinyl]-4,4,5,5-
tetramethyl-1,3,2-dioxaborolane (18): To a stirred solution of BBr3
(6.0 mL, 6.0 mmol, 1.0
M in DCM) in DCM (57 mL) was added 1-
Methyl (2E)-5-(4-Bromo-3-methoxyphenyl)pent-2-en-4-ynoate
(36): 1-Bromo-4-ethynyl-2-methoxybenzene 10 (0.175 g,
0.833 mmol), methyl(2E)-3-iodoprop-2-enoate 35 (0.147 g,
0.694 mmol), bis(triphenylphosphine)palladium(II) dichloride
(49 mg, 0.007 mmol) and copper(I) iodide (1 mg, 0.007 mmol) were
added to a flask, which was then purged with argon for 5 min. Dry,
degassed Et3N (3.9 mL) was then added and the reaction mixture
stirred in the dark at room temperature for 3 d. The solvent was
then evaporated to give 0.347 g of a dark yellow solid. This residue
was then purified using silica gel chromatography, eluent 25 %
EtOAc in hexane. Pure fractions were evaporated to give the desired
product as a yellow solid (0.204 g, 89 %). M.p. 85.8–86.8 °C. 1H NMR
(700 MHz, CDCl3, 25 °C, TMS): δ = 3.78 (s, 3 H), 3.90 (s, 3 H), 6.32 [d,
bromo-4-ethynyl-2-methoxybenzene 10 (1.25 g, 6.0 mmol) in DCM
(10 mL) at –78 °C under a positive pressure of argon. The resulting
purple solution was stirred at –78 °C for 2 h and warmed to 0 °C
before adding sat. NaHCO3 (19 mL). The resulting orange solution
was stirred for 10 min, then transferred to a separating funnel. The
mixture was extracted with DCM (2 × 114 mL) and the organics
washed with H2O (114 mL) and brine (114 mL), dried with MgSO4,
filtered and evaporated to yield a brown oil. This crude residue was
then redissolved in DCM (63 mL) and MgSO4 (1.46 g, 12.1 mmol)
and pinacol (0.716 g, 6 mmol) were added. The reaction mixture
was stirred for 1 h at room temperature, then the solution was
filtered and evaporated to give the desired product as a brown
solid (1.88 g, 75 %). M.p. 74.8–77.0 °C; 1H NMR (700 MHz, CDCl3,
25 °C, TMS): δ = 1.35 (s, 12 H), 3.91 (s, 3 H), 6.43 (s, 1 H), 7.07–7.13
(m, 2 H), 7.49 [d, 3J(H,H) = 8.3 Hz, 1 H] ppm. 11B NMR (128 MHz,
CDCl3, 25 °C, TMS): δ = 29.2 ppm. 13C NMR (176 MHz, CDCl3, 25 °C,
TMS): δ = 25.0, 56.4, 84.2, 111.3, 113.2, 120.9, 133.1, 138.9, 141.8,
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3J(H,H) = 15.8 Hz, 1 H], 6.89–6.99 (m, 3 H), 7.50 [d, J(H,H) = 8.0 Hz,
1 H] ppm. 13C NMR (176 MHz, CDCl3, 25 °C, TMS): δ = 51.9, 56.3,
86.8, 97.4, 113.6, 114.8, 122.3, 124.9, 125.4, 130.0, 133.4, 155.7, 166.2
ppm. IR (film): ν (inter alia) = 1714 (s), 2199 (s), 2947 (w) cm–1. MS
˜
(ASAP) m/z 295.0 [M + H], 297.0 [M + H]. HRMS (ASAP): m/z: calcd.
for C13H12O379Br 294.9969 [M+], found 294.9970. Structure deter-
mined by X-ray crystallography.
155.6 ppm. IR (KBr disk): ν (inter alia) = 2978 (m), 2942 (m) cm–1
.
˜
MS (ASAP) m/z 415.0 [M+], 417.0 [M+], 419.0 [M+]. HRMS (ASAP) m/z
calcd. for C15H1910BO379Br2 414.9830 [M+], found 414.9826. Struc-
ture confirmed by X-ray crystallography.
1-Bromo-4-(1-bromoethenyl)-2-methoxybenzene (34): To a well-
stirred solution of BBr3 (4.8 mL, 4.78 mmol, 1.0
M solution in DCM)
2-[(E)-2-(4-Bromo-3-methoxyphenyl)ethenyl]-4,4,5,5-tetra-
methyl-1,3,2-dioxaborolane (19): Copper(I) chloride (16 mg,
0.158 mmol), xantphos (92 mg, 0.158 mmol), sodium tert-butoxide
(31 mg, 0.32 mmol) and 4,4,5,5-tetramethyl-2-(tetramethyl-1,3,2-di-
oxaborolan-2-yl)-1,3,2-dioxaborolane (1.33 g, 5.28 mmol) were
added to a dry flask fitted with a Schlenk tap under argon. Dry THF
(11 mL) was then added and the reaction mixture stirred for 5 min.
1-bromo-4-ethynyl-2-methoxybenzene 10 (1.11 g, 5.28 mmol) was
then added and the reaction mixture stirred for 5 min, then dry
MeOH (0.42 mL) was added. The reaction mixture was stirred at
room temperature overnight. The reaction mixture was diluted with
EtOAc (110 mL) and washed with H2O (105 mL) and then saturated
brine (105 mL). The organics were dried with MgSO4, filtered and
evaporated to yield 2.40 g of a dark yellow oil. The crude product
was purified by silica gel chromatography, eluent 0–5 % EtOAc in
hexane to yield the desired product as a yellow oil, which became
a yellow solid on standing (1.40 g, 79 %). M.p. 66.9–69.3 °C. 1H NMR
(400 MHz, CDCl3, 25 °C, TMS): δ = 1.31 (s, 12 H), 3.90 (s, 3 H), 6.16
[d, 3J(H,H) = 18.4 Hz, 1 H], 6.91–7.06 (m, 2 H), 7.33 [d, 3J(H,H) =
18.4 Hz, 1 H], 7.49 [d, 3J(H,H) = 8.1 Hz, 1 H] ppm. 11B NMR (128 MHz,
CDCl3, 25 °C, TMS): δ = 29.7 ppm. 13C NMR (101 MHz, CDCl3, 25 °C,
TMS): δ = 25.0, 56.2, 83.7, 110.1, 112.5, 120.8, 133.5, 138.4, 148.6,
in DCM (45 mL) at –78 °C was added a solution of 1-bromo-4-
ethynyl-2-methoxybenzene 10 (1.0 g, 4.78 mmol) dropwise. The re-
sulting deep pink solution was then stirred at –78 °C for 3 h. The
reaction mixture was then warmed to 0 °C and sat. NaHCO3 (15 mL),
followed by Et2O (30 mL), were added dropwise at 0 °C. The now
pale yellow reaction mixture was then stirred at this temperature
for 2 h. The reaction mixture was then transferred to a separating
funnel and the layers separated. The aqueous layer was then
washed with DCM (2 × 100 mL), then the organics was with H2O
(100 mL) and then brine (100 mL). The organics were then dried
with MgSO4, filtered and evaporated to yield 1.4 g of a pale yellow
solid. The crude solid was then purified by silica gel chromatogra-
phy, elution gradient 0 % to 10 % to 50 % EtOAc in hexane. Pure
fractions were evaporated to give 0.411 g of a pale yellow solid
containing 41 % desired product (0.173 g, 13 %). 1H NMR (600 MHz,
3
CDCl3, 25 °C, TMS): δ = 3.93 (s, 3 H), 5.80 [d, J(H,H) = 2.1 Hz, 1 H],
6.12 (d, J = 2.1 Hz, 1 H), 7.02–7.12 (m, 2 H), 7.50 [d, 3J(H,H) = 8.2 Hz,
1 H] ppm. 13C NMR (151 MHz, CDCl3, 25 °C, TMS): δ = 56.4, 111.2,
112.7, 118.4, 120.5, 129.7, 132.92, 139.2, 156.5 ppm. IR: ν (inter
˜
alia) = 2836 (m), 2943 (m), 2970 (m) cm–1. MS (ASAP) m/z 289.9
[M+], 291.9 [M+], 293.9 [M+]. HRMS (ASAP) m/z calcd. for C9H8O79Br2
289.8959 [M+], found 289.8942.
156.1 ppm. IR (film): ν(inter alia) = 1548 (m), 1620 (m) cm–1. MS
˜
(ESI) m/z 339.1 [M + H], 341.1 [M + H]. HRMS (ESI) m/z calcd. for Methyl (2E,4Z)-5-Bromo-5-(4-bromo-3-methoxyphenyl)penta-
C15H2110BO379Br 338.0803 [M+], found 338.0814.
2,4-dienoate (37): 2-[(Z)-2-Bromo-2-(4-bromo-3-methoxy-
Eur. J. Org. Chem. 0000, 0–0
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