The Journal of Organic Chemistry
Note
Preparation of 2-Methyl-6-(trimethylsilyl)phenyl Trifluoro-
methanesulfonate (3f). A mixture of 2-bromo-6-methylphenol (10
mmol), TMSCl (10 mmol), and THF (20 mL) was cooled to 0 °C
under an Ar atmosphere. To the solution was added dropwise
triethylamine (10 mmol), and the resulting solution was allowed to
warm to room temperature. After stirring for 2 h, white precipitate was
filtered off and the filtrate was concentrated under vacuum to afford
the crude mixture of (2-bromo-6-methylphenoxy)trimethylsilane. The
crude mixture was placed in 100 mL round bottled flask and diluted
with THF (20 mL) under Ar atmosphere. The mixture was cooled to
−78 °C and n-BuLi in hexane (1.65 M, 9.1 mL, 15 mmol) was added
slowly. The whole mixture was stirred for 1h at −78 °C. Then, Tf2O
(15 mmol) was added via syringe and the resulting solution was
allowed to warm to room temperature. After stirring for 1 h, the
reaction was quenched by adding H2O and the mixture was extracted
with Et2O (2 × 20 mL). The combined organic layer was subsequently
washed with NaHCO3 aq. and brine, and dried over MgSO4. After
filtration and removal of all volatiles, purification of the residue by
silica gel chromatography using hexane as an eluent gave 3f (Colorless
oil, 1.7 g, 5.3 mmol, 53%). 1H NMR (500 MHz, CDCl3): δ 7.39 (d, J =
6.7 Hz, 1H), 7.29−7.25 (m, 2H), 2.38 (s, 3H), 0.38 (s, 9H). 13C NMR
(126 MHz, CDCl3): δ 151.1, 134.8, 134.5, 133.7, 131.4, 127.9, 118.6
(q, JC−F = 319.8 Hz), 17.3, 0.1. ESI-HRMS (m/z): [M−H]− calcd for
C11H14F3O3SSi, 311.0390; found, 311.0392.
A Procedure for Carboxylation of 1a (Table 1, entry 5). A 20
mL Schlenk flask was charged with Mn powder (21 mg, 0.38 mmol)
and dried with a heating-gun under vacuum. Then, the flask was
charged with CoI2(L3) (6.5 mg, 0.013 mmol). The flask was evacuated
and refilled with CO2. This sequence was repeated five times. Then,
DMA (0.50 mL) and 1a (59 μL, 0.25 mmol) were added via airtight
syringes, and the resulting mixture was stirred at room temperature for
20 h. After the reaction, tridecane (50 μL, 0.21 mmol) as an internal
standard, Et2O (5 mL), and 1 M HCl aq. (3 mL) were added to the
reaction mixture. After stirring for 10 min, the organic layer was
separated, dried over MgSO4, and filtrated. Then, methanol (1 mL)
and TMSCHN2 (2.0 M in Et2O, 0.5 mL, 1.0 mmol) were added to the
resulting solution, and it was stirred for 10 min. The yield of 2a-Me
was determined by GC analysis.
C10H13O4, 197.0819; found, 197.0815. IR (neat): 3100−2800 (br),
1720.5, 1683.9, 1645.3, 1379.1, 1249.9, 1174.7, 1141.9, 1089.8, 1033.9,
856.4, 763.8 cm−1.
4-{4-[(4-Methylbenzenesulfonyl)oxy]phenyl}cyclohex-1-ene-1-
carboxylic Acid (2d). White solid (62 mg, 67%); mp 238−240 °C; 1H
NMR (500 MHz, DMSO−D6): δ 12.17 (br s, 1H), 7.74 (d, J = 8.2 Hz,
2H), 7.47 (d, J = 7.9 Hz, 2H), 7.27 (d, J = 8.9 Hz, 2H), 6.95−6.90 (m,
3H), 2.78−2.72 (m, 1H), 2.42−2.19 (m, 7H), 1.86−1.84 (m, 1H),
1.68−1.60 (m, 1H). 13C NMR (126 MHz, DMSO−D6): δ 167.9,
147.3, 145.7, 145.3, 138.1, 131.6, 130.2, 130.1, 128.3, 128.1, 121.8,
37.7, 32.8, 28.9, 24.4, 21.1. ESI-HRMS (m/z): [M−H]− calcd for
C20H19O5S, 371.0959; found, 371.0953. IR (neat): 3100−2800 (br),
1716.7, 1681.9, 1674.2, 1558.5, 1541.1, 1506.4, 1456.3, 1373.3, 1278.8,
1197.8, 1174.7, 1153.4, 1089.8, 864.1, 750.3, 723.3 cm−1.
6-Methylcyclohex-1-ene-1-carboxylic Acid (2e).8d White solid (25
1
mg, 70%); H NMR (500 MHz, CDCl3): δ 7.10 (t, J = 4.0 Hz, 1H),
2.72−2.66 (m, 1H), 2.28−2.12 (m, 2H), 1.67−1.55 (m, 4H), 1.11 (d, J
= 7.0 Hz, 3H). 13C NMR (126 MHz, CDCl3): δ 173.1, 142.2, 134.7,
29.5, 27.5, 26.2, 20.2, 17.0.
3-(1-Methyl-1H-indol-3-yl)cyclohex-1-ene-1-carboxylic Acid (2f).
1
White solid (53 mg, 83%); mp 166−168 °C; H NMR (500 MHz,
CDCl3): δ 10.89 (brs, 1H), 7.59 (d, J = 7.9 Hz, 1H), 7.29−7.28 (m,
2H), 7.24−7.21 (m, 1H), 7.11 (t, J = 7.3 Hz, 1H), 6.76 (s, 1H), 3.88
(brs, 1H), 3.71 (s, 3H), 2.38−2.35 (m, 2H), 2.06−2.01 (m, 1H),
1.83−1.75 (m, 2H), 1.71−1.66 (m, 1H). 13C NMR (126 MHz,
CDCl3): δ 173.3, 144.7, 137.2, 129.8, 126.7, 126.4, 121.7, 118.9, 118.9,
116.9, 109.3, 33.4, 32.6, 29.2, 23.9, 20.4. ESI-HRMS (m/z): [M−H]−
calcd for C16H16NO2, 254.1187; found, 254.1185. IR (neat): 3100−
2800 (br), 1716.6, 1670.3, 1626.0, 1558.5, 1541.1, 1506.4, 1473.6,
1456.3, 1288.5, 1257.6, 808.2, 733.0 cm−1.
3-(5-Methylfuran-2-yl)cyclohex-1-ene-1-carboxylic Acid (2g). Yel-
low solid (41 mg, 80%); mp 97−99 °C; 1H NMR (500 MHz, CDCl3):
δ 7.16−7.14 (m, 1H), 5.88 (d, J = 3.1 Hz, 1H), 5.86 (d, J = 3.1 Hz,
1H), 3.62−3.59 (m, 1H), 2.33−2.29 (m, 2H), 2.26 (s, 3H), 2.00−1.95
(m, 1H), 1.86−1.79 (m, 1H), 1.77−1.70 (m, 1H), 1.69−1.61 (m, 1H).
13C NMR (126 MHz, CDCl3): δ 173.0, 154.4, 151.0, 141.3, 130.6,
105.9 (two peaks overlap absolutely, confirmed with the HMQC and
HMBC spectra), 35.8, 27.1, 23.8, 20.2, 13.5. ESI-HRMS (m/z): [M−
H]− calcd for C12H13O3, 205.0870; found, 205.0867. IR (neat): 3100−
2800 (br), 1683.9, 1635.6, 1558.5, 1508.3, 1417.7, 1288.5, 1020.3,
788.9 cm−1.
Representative Procedure for the Carboxylation of Alkenyl
Triflates (1b−n) and Aryl Triflates (3a−g). A 20 mL Schlenk flask
was charged with Mn powder (21 mg, 0.38 mmol) and dried with a
heating gun under vacuum. Then, the flask was charged with CoI2(L3)
(6.5 mg, 0.013 mmol). The flask was evacuated and refilled with CO2.
This sequence was repeated five times. Then, DMA (0.50 mL) and 1
(0.25 mmol) were added via airtight syringes, and the resulting
mixture was stirred at room temperature for 20 h. After the reaction, 1
M HCl aq. (3 mL) and Et2O (5 mL) were added, and the whole
solution was stirred at room temperature for 10 min. The mixture was
extracted with Et2O (5 mL × 5). The collected organic layer was
combined and dried over anhydrous MgSO4. After removal of
volatiles, the residue was purified by silica gel chromatography using
hexane/acetone (6/1, v/v) as an eluent.
3,4-Dihydronaphthalene-2-carboxylic Acid (2h).22 Pale yellow
1
solid (34 mg, 78%); H NMR (500 MHz, DMSO-d6): δ 12.45 (br s,
1H), 7.47 (s, 1H), 7.32 (d, J = 7.0 Hz, 1H), 7.28−7.21 (m, 3H), 2.81
(t, J = 8.4 Hz, 2H), 2.47 (t, J = 8.4 Hz, 2H). 13C NMR (126 MHz,
DMSO-d6): δ 168.0, 136.5, 135.4, 132.3, 129.9, 129.3, 128.3, 127.5,
126.7, 26.9, 21.9.
3,4-Dihydronaphthalene-1-carboxylic Acid (2i).23 Pale yellow
1
solid (23 mg, 53%); H NMR (500 MHz, CDCl3): δ 7.91 (d, J =
7.6 Hz, 1H), 7.41 (t, J = 4.7 Hz, 1H), 7.26−7.16 (m, 3H), 2.78 (t, J =
7.8 Hz, 2H), 2.47−2.43 (m, 2H). 13C NMR (126 MHz, CDCl3): δ
171.9, 143.0, 136.2, 130.4, 129.9, 127.7, 127.5, 126.6, 126.2, 27.4, 23.7.
7-Chloro-3,4-dihydronaphthalene-1-carboxylic Acid (2j). White
4-Phenylcyclohex-1-ene-1-carboxylic Acid (2a).4b White solid (40
mg, 79%); 1H NMR (500 MHz, CDCl3): δ 7.33−7.30 (m, 2H), 7.23−
7.21 (m, 4H), 2.83−2.77 (m, 1H), 2.58−2.51 (m, 2H), 2.38−2.31 (m,
2H), 2.07−2.03 (m, 1H), 1.80−1.72 (m, 1H). 13C NMR (126 MHz,
CDCl3): δ 172.9, 145.8, 141.8, 129.7, 128.5, 126.8, 126.3, 39.0, 33.9,
29.3, 24.4.
1
solid (24 mg, 45%); mp 189−191 °C; H NMR (500 MHz, acetone-
d6): δ 8.03 (s, 1H), 7.38 (t, J = 4.9 Hz, 1H), 7.21 (app. d, J = 1.2 Hz,
2H), 2.76 (t, J = 7.9 Hz, 2H), 2.44 (td, J = 8.0, 5.0 Hz, 2H). 13C NMR
(126 MHz, acetone-d6): δ 166.3, 142.4, 135.1, 132.9, 131.5, 128.98,
128.96, 127.1, 126.0, 26.4, 23.2. ESI-HRMS (m/z): [M−H]− calcd for
C11H8ClO2, 207.0218; found, 207.0215. IR (neat): 3100−2800 (br),
1716.7, 1683.9, 1558.5, 1541.1, 1506.4, 1489.1, 1473.6, 1456.3, 1174.7,
889.2, 835.2, 814.0, 715.6 cm−1.
4-tert-Butylcyclohex-1-ene-1-carboxylic Acid (2b).21 White solid
1
(34 mg, 74%); H NMR (500 MHz, CDCl3): δ 7.14−7.12 (m, 1H),
2.52−2.48 (m, 1H), 2.31−2.25 (m, 1H), 2.16−2.08 (m, 1H), 2.00−
1.90 (m, 2H), 1.31−1.25 (m, 1H), 1.18−1.10 (m, 1H), 0.89 (s, 9H).
13C NMR (126 MHz, CDCl3): δ 173.0, 143.0, 129.6, 43.2, 32.1, 27.7,
27.1, 25.2, 23.5.
Cyclohep-1-ene-1-carboxylic Acid (2k).21 Pale yellow solid (26 mg,
1
75%); H NMR (500 MHz, CDCl3): δ 7.35 (t, J = 6.7 Hz, 1H), 2.52
(dd, J = 5.5, 5.5 Hz, 2H), 2.32 (dd, J = 11.3, 6.4 Hz, 2H), 1.81−1.76
(m, 2H), 1.58−1.51 (m, 4H). 13C NMR (126 MHz, CDCl3): δ 173.8,
147.3, 135.9, 32.0, 29.0, 36.9, 26.1, 25.6.
4-(Ethoxycarbonyl)cyclohex-1-ene-1-carboxylic Acid (2c). White
1
solid (38 mg, 76%); mp 97−98 °C; H NMR (500 MHz, CDCl3): δ
7.12−7.10 (br m, 1H), 4.18−4.14 (m, 2H), 2.59−2.45 (m, 4H), 2.29−
2.22 (m, 1H), 2.13−2.08 (m, 1H), 1.76−1.68 (m, 1H), 1.27 (t, J = 7.2
Hz, 3H). 13C NMR (126 MHz, CDCl3): δ 175.0, 172.3, 140.2, 129.3,
60.6, 38.2, 28.0, 24.7, 23.1, 14.2. ESI-HRMS (m/z): [M−H]− calcd for
2-Cyclohexylideneacetic Acid (2l).24 White solid (15 mg, 43%); 1H
NMR (500 MHz, CDCl3): δ 5.63 (s, 1H), 2.83 (t, J = 5.8 Hz, 2H),
2.22 (t, J = 6.1 Hz, 2H), 1.68−1.59 (m, 6H). 13C NMR (126 MHz,
CDCl3): δ 172.2, 166.8, 112.5, 38.3, 30.1, 28.7, 27.9, 26.2.
D
J. Org. Chem. XXXX, XXX, XXX−XXX