ACS Catalysis
Research Article
5a (x = 8): 1H NMR (CDCl3, 400 MHz, 25 °C) δ = 11.08 (s,
br. 1H, COOH), 3.66 (s, 3H, H-1), 2.34 (t, 3JHH = 7.5 Hz, 2H, H-
3′), 2.30 (t, 3JHH = 7.5 Hz, 2H, H-3), 1.67−1.57 (m, 4H, H-4, H-
4′), 1.38−1.22 (m, 26H, H-5) ppm; 13C{1H} NMR (CDCl3, 100
MHz, 25 °C) δ = 179.4 (C-2′), 174.6 (C-2), 51.6 (C-1), 34.3 (C-
3), 34.1 (C-3′), 29.8−29.2 (C-5), 25.1 (C-4), 24.8 (C-4′) ppm.
Elemental analysis (%) calcd: 70.13 (C), 11.18 (H). Found:
70.18 (C), 11.20 (H). APCI-MS (m/z): 343.1 [M + H]+.
5b (x = 1): 1H NMR (CDCl3, 400 MHz, 25 °C) δ = 11.52 (s,
br. 1H, COOH), 3.65 (s, 3H, H-1), 2.33 (t, 3JHH = 7.5 Hz, 2H, H-
3′), 2.28 (t, 3JHH = 7.6 Hz, 2H, H-3), 1.66−1.56 (m, 4H, H-4, H-
4′), 1.36−1.22 (m, 26H, H-5) ppm; 13C{1H} NMR (CDCl3, 100
MHz, 25 °C) δ = 180.2 (C-2′), 174.5 (C-2), 51.6 (C-1), 34.2 (C-
3), 34.2 (C-3′), 29.5−29.1 (C-5), 25.1 (C-4), 24.8 (C-4′) ppm.
Elemental analysis (%) calcd: 63.91 (C); 9.90 (H). Found: 63.68
(C), 10.13 (H). APCI-MS (m/z): 245.0 [M + H]+.
Hz, 2H, H-3), 1.68−1.53 (m, 4H, H-4, H-4′), 1.35−1.16 (m,
28H, H-5) ppm; 13C{1H} NMR (100 MHz, CDCl3, 25 °C) δ
174.4 (C-2), 168.6 (C-2′), 133.9−123.2 (C-1′), 51.5 (C-1), 38.2
(C-3′), 34.2 (C-3), 29.8−27.0 (C-‘4, C-5), 25.1 (C- 4) ppm.
Elemental analysis (%) calcd: 73.49 (C), 9.47 (H), 3.06 (N).
Found: 73.81 (C), 9.66 (H), 3.38 (N). APCI-MS (m/z): 458.1
[M + H]+.
From the crude product, the desired linear nitrile ester 13 was
isolated by repetitive recrystallization from methanol to yield the
pure 1,19-difunctional compound in a purity >99% in 58% yield
(as determined by GC analysis).
General Procedure for the Synthesis of ω-Hydroxy
Esters. According to a procedure by Gorczynski et al.,19 the
monoester was dissolved in dry THF in a flame-dried round-
bottom flask with argon inlet and cooled to 0 °C. Over a period of
45 min, 1.1 equiv of BH3·THF complex (1.0 M in THF) was
added dropwise to the cooled solution. The reaction mixture was
stirred at 0 °C for 30 min and then was stirred for 14 h at room
temperature. The resulting slurry was quenched with 100 mL of
water, the water phase was saturated with K2CO3, and the phases
were separated. The water phase was washed with Et2O, and the
combined organic layer was washed with brine and dried over
MgSO4. The crude product obtained after removal of the solvent
by rotary evaporation was purified by column chromatography
using CH2Cl2/EtOAc, 8/2, to yield the desired compounds as a
white solid in 84% (6a) and 51% (6b), respectively.
13: 1H NMR (400 MHz, CDCl3, 25 °C) δ 3.64 (s, 3H, H-1),
2.31 (t, 3JHH = 7.2 Hz, 2H, H-8), 2.28 (t, 3JHH = 7.5 Hz, 2H, H-3),
1.67−1.57 (m, 4H, H-4, H-7), 1.45−1.39 (m, 2H, H-6), 1.33−
1.18 (m, 24H, H-5) ppm; 13C{1H} NMR (100 MHz, CDCl3, 25
°C) δ 174.4 (C-2), 119.9 (C-9), 51.5 (C-1), 34.2 (C-3), 29.7−
28.8 (C-5, C-6), 25.5 (C-7), 25.1 (C-4), 17.2 (C-8), ppm.
Elemental analysis (%) calcd: 74.25 (C), 11.53 (H), 4.33 (N).
Found: 74.46 (C), 11.53 (H), 4.44 (N). APCI-MS (m/z): 324.1
[M + H]+.
General Procedure for Isomerizing Alkoxycarbonyla-
tion with Monitoring over Time. In the case of solid fatty acid
substrates, the starting material (150.00 mmol)29 was weighed in,
and the assembled reactor was evacuated and purged with argon
several times. In a glovebox in a Schlenk tube equipped with a
magnetic stir bar, the catalyst precursor 1 (958.9 mg, 1.20 mmol)
was weighed in. Another Schlenk tube was charged with 120 mL
of alcohol and 96.9 μL of pyridine (94.9 mg, 1.20 mmol). In the
case of utilization of liquid fatty acid derivative starting materials,
150.00 mmol of substrate was also added at this point. The
mixture was cannula-transferred into the preheated reactor in an
argon counter stream. Successively, the catalyst precursor was
dissolved in 20 mL of the alcohol and cannula-transferred into
the reactor. The reactor was pressurized with carbon monoxide
and stirred at the desired temperature. For the alkoxycarbony-
lation of ethylene, the reactor was pressurized with 5 bar of
ethylene prior to CO addition. Samples of ∼4 mL were retrieved
via a sampling valve at the bottom of the reactor at certain points
in time, diluted with dichloromethane, and filtered over a silica
plug. The solvent was removed in vacuo, and the residue was
analyzed by GC or 1H NMR spectroscopy.
6a (x = 8): 1H NMR (CDCl3, 400 MHz, 25 °C) δ = 3.66 (s,
3H, H-1), 3.64 (t, 3JHH = 6.6 Hz, 2H, H-8), 2.28 (t, 3JHH = 7.6 Hz,
2H, H-3), 1.66−1.52 (m, 4H, H-4, H-7), 1.39−1.20 (m, 28H, H-
5, H-6) ppm; 13C{1H}-NMR (CDCl3, 100 MHz, 25 °C) δ =
174.5 (C-2), 63.2 (C-8), 51.6 (C-1), 34.3 (C-3), 33.0 (C-7),
29.8−29.3 (C-5), 25.9 (C-6), 25.1 (C-4) ppm. Elemental
analysis (%) calcd: 73.12 (C), 12.27 (H). Found: 73.10 (C),
12.25 (H). APCI-MS (m/z): 329.1 [M + H]+.
6b (x = 1): 1H NMR (CDCl3, 400 MHz, 25 °C) δ = 3.65 (s,
3H, H-1), 3.62 (t, 3JHH = 6.6 Hz, 2H, H-8), 2.30 (t, 3JHH = 7.6 Hz,
2H, H-3), 1.65−1.50 (m, 4H, H-4, H-7), 1.46 (s, br, 1H, OH),
1.37−1.23 (m, 14H, H-5, H-6) ppm; 13C{1H}-NMR (CDCl3,
100 MHz, 25 °C) δ = 174.5 (C-2), 63.1 (C-8), 51.5 (C-1), 34.2
(C-3), 32.9 (C-7), 29.7−29.2 (C-5), 25.9 (C-6), 25.1 (C-4) ppm.
Elemental analysis (%) calcd: 67.79 (C), 13.38 (H). Found:
67.97 (C), 11.22 (H). APCI-MS (m/z): 230.9 [M + H]+.
General Procedure for the Preparation of Polyamides.
In a 20 mL stainless steel pressure reactor, a glass inlay was
charged with 1.00 g of ω-amino ester and 4.00 mL of distilled
water. The reactor was closed and degassed prior to pressurizing
with 10 bar of nitrogen. After heating to 190 °C for 3.5 h, the
pressure was slowly released, and vacuum was applied for 4 h.
General Procedure for the Cleavage of Benzyl Esters.
The hydrogenolysis of benzyl methyl esters was typically
performed according to a standard procedure for hydrogenolysis
of benzyl esters.15 In a round-bottom flask with an argon inlet,
benzyl methyl ester and 0.1 wt % Pd/C (10 wt %) were
suspended in 50 mL of dry THF. The flask was purged with
hydrogen and closed with a septum stopper. A balloon with
hydrogen was attached to the flask, and the slurry was stirred at
room temperature overnight. The mixture was filtered over a
silica plug with CH2Cl2/THF, 7/3. After the solvent was
removed by rotary evaporation, the crude product was used
without further purification.
4527
ACS Catal. 2015, 5, 4519−4529