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until neutral pH was reached. After organic layer was evaporated
under reduced pressure, the solid product was washed with pen-
tane, and 6 was obtained as a blue solid (9 mg, 67%). 1H NMR
(300 MHz, CDCl3, 258C, TMS): d=8.81 (s, 2H), 8.80–8.73 (m, 4H),
8.72–8.67 (m, 2H), 8.31 (s, 2H), 8.13–8.07 (m, 2H), 7.90 (td, J=7.77,
1.76 Hz, 2H), 7.83–7.77 (m, 2H), 7.54–7.49 (m, 2H), 7.37 (ddd, J=
7.40, 4.76, 1.03 Hz, 2H), 3.74 (brs, 4H), 2.77 (brs, 4H), 2.04 ppm
(brs, 8H); 13C NMR (75 MHz, CDCl3, 258C, TMS): d=164.35, 161.31,
156.42, 156.25, 150.21, 149.75, 149.42, 138.98, 137.10, 136.91,
135.78, 130.89, 130.01, 129.57, 129.32, 128.88, 128.61, 124.08,
123.89, 121.59, 119.29, 119.20, 119.00, 118.40, 117.67, 52.71, 25.99,
14.37 ppm; UV/Vis (CHCl3): lmax (e)=683 (16605), 644 (17005), 561
(16030), 275 nm (43705 molÀ1 dm3 cmÀ1); MS (ESI-TOF, CHCl3/MeOH
10:15): m/z calcd for C53H36N6O5: 837.2825; found: 837.2845
[M+H]+.
Compound 10: A mixture 9[20] (146 mg, 0.180 mmol), 4-nitrophe-
nylboronic acid (67 mg, 0.396 mmol), TBACl (67 mg, 0.036 mmol),
Pd(dppf)Cl2·CH2Cl2 (12 mg, 0.014 mmol), K2CO3 (1m, 8.3 mL), and
toluene (8.3 mL) was heated at 908C under an argon atmosphere
for 3 h. The reaction mixture was cooled to RT, and then organic
phase was separated, washed with water (3), and evaporated
under reduced pressure. The crude product was purified by
column chromatography on silica gel 60 (hexane/EtOAc 4:1) and
10 was obtained as an orange solid (116 mg, 72%). 1H NMR
(300 MHz, CDCl3, 258C, TMS): d=8.29 (d, J=8.79 Hz, 4H), 7.98 (s,
2H), 7.64 (d, J=8.21 Hz, 4H), 7.52 (d, J=7.91 Hz, 2H), 7.25 (d, J=
7.91 Hz, 2H), 4.33 (q, J=7.04 Hz, 8H), 1.83–1.71 (m, 8H), 1.52–1.42
(m, 8H), 0.98 ppm (t, J=7.3 Hz, 12H); 13C NMR (75 MHz, CDCl3,
258C, TMS): d=168.30, 168.16, 149.24, 147.58, 136.76, 133.68,
131.98, 131.57, 131.37, 130.80, 130.56, 130.44, 130.02, 129.13,
127.56, 125.24, 66.01, 65.97, 30.82, 19.46, 19.43, 14.03, 14.01 ppm;
MS (ESI-TOF, CHCl3/MeOH 10:15): m/z calcd for C52H50N2O12:
894.3364; found: 894.3412 [M]+.
Synthesis
Compound 3: Anhydride 2[17] (40 mg, 0.077 mmol), 1[18] (30 mg,
0.092 mmol), and imidazole (383 mg, 5.6 mmol) were dissolved tol-
uene (3 mL). The reaction mixture was stirred at 1408C for 4 h.
After cooling to 708C, the mixture was adjusted to pH 6 by adding
EtOH (2 mL) and HCl (2m, 1 mL). The solution was diluted with tol-
uene and washed with water (3). The organic phase was evapo-
rated under reduced pressure. The crude product was purified by
column chromatography on aluminum oxide (CHCl3) to give 3 as
a dark-red solid (57 mg, 90%). 1H NMR (300 MHz, CDCl3, 258C,
TMS): d=8.82 (s, 2H), 8.77–8.73 (m, 2H), 8.72–8.66 (m, 4H), 8.50
(dd, J=10.85, 8.21 Hz, 4H), 8.17–8.09 (m, 4H), 7.89 (td, J=7.77,
1.76 Hz, 2H), 7.58–7.51 (m, 2H), 7.37 (ddd, J=7.40, 4.76, 1.32 Hz,
2H), 4.36 (t, J=6.74 Hz, 4H), 1.86–1.75 (m, 4H), 1.55–1.44 (m, 4H),
1.01 ppm (t, J=7.48 Hz, 6H); 13C NMR (75 MHz, CDCl3, 258C, TMS):
d=168.41, 163.77, 156.35, 156.20, 149.56, 149.39, 139.04, 136.99,
136.26, 135.80, 132.17, 132.04, 131.79, 130.49, 129.57, 129.25,
129.06, 128.55, 126.12, 124.02, 122.89, 122.21, 122.04, 121.48,
119.13, 65.84, 30.87, 19.52, 14.07 ppm; UV/Vis (CHCl3): lmax (e)=509
(36060), 478 (28090), 277 nm (29995 molÀ1 dm3 cmÀ1); MS (ESI-TOF,
CHCl3/MeOH 10:15): m/z calcd for C53H40N4O6: 829.3026; found:
829.2980 [M+H]+.
Compound 4: PMI diester 3 (20 mg, 0.024 mmol) and p-TsOH·H2O
(23 mg, 0.12 mmol) were added to toluene (2 mL). The reaction
mixture was stirred at 1008C for 23 h. After cooling to RT, the mix-
ture was evaporated under reduced pressure. The crude product
was transferred to a centrifuge tube with water, and spun approxi-
mately ten times in a centrifuge (the water was changed every
time). Product 4 was dried in a desiccator and obtained as a red
solid (16 mg, 94%). No NMR data is available because of poor solu-
bility; UV/Vis (CHCl3): lmax (e)=522 (19500), 485 (15570), 456
(12555), 281 nm (19910 molÀ1 dm3 cmÀ1); MS (ESI-TOF, CHCl3/MeOH
10:15): m/z calcd for C45H22N4O5: 699.1669; found: 699.1559
[M+H]+.
Compound 11: 4-Nitrophenyl PTE 10 (116 mg, 0.129 mmol) was
heated at 958C in a mixture of toluene/heptane (5:1) until com-
plete dissolution was achieved. p-TsOH·H2O (30 mg, 0.157 mmol)
was added and the mixture was stirred for 5 h at 958C (monitored
by TLC). The mixture was cooled to RT, and the precipitate was
filtered and washed with heptane. The crude red solid was used in
the next step without further purification.
Compound 5: PMI diester 3 (30 mg, 0.036 mmol) and CuCl2 (5 mg,
0.036 mmol) were dissolved in pyrrolidine (4.3 mL), and stirred at
RT under a drying tube for 44 h. The reaction mixture was evapo-
rated under reduced pressure, and MeOH was added twice during
the evaporation before the crude product was evaporated to dry-
ness. The product was dissolved in CHCl3 and washed with water
(4). Purification by preparative TLC (aluminum oxide, CHCl3/
hexane 4:1; a second purification was needed for part of the prod-
Compounds 12 and 13: A mixture of 11 (65 mg, 0.084 mmol), imi-
dazole (424 mg, 6.2 mmol), and 1 (55 mg, 0.169 mmol) in toluene
(2 mL) was stirred at 1408C for 4 h. On completion, the reaction
mixture was cooled to 608C and ethanol (5 mL) was added. The
mixture was neutralized by dropwise addition of HCl (2m) then ex-
tracted with toluene (3). The organic phase was washed with
water (2), dried over Na2SO4, and concentrated under reduced
pressure. The crude product was purified by column chromatogra-
phy on silica gel 60 (CHCl3/hexane 4:1) to give product 12 (52 mg,
57%) and byproduct 13 (11 mg, 10%) as dark-red solids.
PMI 12: 1H NMR (300 MHz, CDCl3, 258C, TMS): d=8.79 (s, 2H),
8.74–8.69 (m, 2H), 8.68–8.63 (m, 2H), 8.61 (s, 1H), 8.35 (t, J=
8.94 Hz, 4H), 8.16–8.05 (m, 3H), 8.02 (s, 1H), 7.87 (td, J=7.70,
1.91 Hz, 2H), 7.78–7.66 (m, 5H), 7.63–7.56 (m, 1H), 7.48 (d, J=
8.79 Hz, 2H), 7.42–7.32 (m, 3H), 4.42–4.32 (m, 4H), 1.87–1.75 (m,
4H), 1.56–1.42 (m, 4H), 1.00 ppm (td, J=7.33, 1.76 Hz, 6H);
13C NMR (75 MHz, CDCl3, 258C, TMS): d=168.11, 168.03, 163.47,
163.44, 156.30, 156.27, 149.51, 149.41, 148.92, 148.75, 147.93,
147.91, 139.47, 138.16, 137.80, 137.06, 135.82, 135.29, 135.06,
134.26, 133.73, 131.88, 131.71, 131.63, 131.59, 131.13, 130.64,
130.51, 130.26, 129.40, 129.27, 129.07, 128.75, 128.29, 128.00,
125.64, 125.50, 124.10, 122.10, 121.65, 121.53, 119.20, 66.28, 66.24,
30.83, 30.79, 19.49, 19.44, 14.03 ppm; UV/Vis (CHCl3): lmax (e)=492
1
uct) gave 5 as a dark-blue solid (16 mg, 46%). H NMR (300 MHz,
CDCl3, 258C, TMS): d=8.83 (s, 2H), 8.78–8.74 (m, 2H), 8.73–8.67 (m,
4H), 8.18–8.10 (m, 2H), 7.89 (td, J=7.77, 1.76 Hz, 2H), 7.84 (s, 2H),
7.54 (dd, J=8.35, 2.20 Hz, 4H) 7.36 (ddd, J=7.33, 4.69, 1.17 Hz,
2H), 4.34 (t, J=6.89 Hz, 4H), 3.73 (brs, 4H), 2.76 (brs, 4H), 2.15–
1.86 (m, 8H), 1.85–1.73 (m, 4H), 1.54–1.43 (m, 4H) 1.00 ppm (t, J=
7.62 Hz, 6H); 13C NMR (75 MHz, CDCl3, 258C, TMS): d=168.63,
164.70, 156.50, 156.25, 150.17, 149.94, 149.43, 138.71, 137.47,
137.12, 137.05, 132.98, 131.54, 130.80, 129.71, 129.10, 128.73,
128.56, 124.02, 122.90, 121.58, 119.27, 116.28, 115.81, 112.47, 65.67,
52.72, 30.88, 26.01, 19.49, 14.08 ppm; UV/Vis (CHCl3): lmax (e)=649
(22100), 609 (18165), 531 (13220), 281 nm (38215 molÀ1 dm3 cmÀ1);
MS (ESI-TOF, CHCl3/MeOH 10:15): m/z calcd for C61H54N6O6:
967.4183; found: 967.4149 [M+H]+.
Compound 6: PMI diester 5 (16 mg, 0.017 mmol) and p-TsOH·H2O
(16 mg, 0.083 mmol) were dissolved in toluene (2 mL), and the
mixture was stirred at 1008C for 5 d. After 4 d, more p-TsOH·H2O
(5 mg) was added and the reaction mixture was stirred for 1 day
more. The mixture was evaporated under reduced pressure then
dissolved in CHCl3. The organic phase was washed with water (4)
Chem. Eur. J. 2016, 22, 1501 – 1510
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