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S. Tanaka et al. / Tetrahedron Letters xxx (xxxx) xxx
Procedure for catalytic transesterification
1.81 (2 H, m, ACH2A), 4.37 (2 H, t, J = 6.8 Hz, CH2AOCO), 8.21 (2
H, d like, J = 8.9 Hz, ArH), 8.29 (2 H, d like, J = 8.9 Hz, ArH); 13C
NMR (CDCl3, 125 MHz) d 14.0, 22.5, 25.6, 28.5, 31.4, 66.1, 123.5,
130.6, 135.9, 150.5, 164.7; Elemental analysis calcd (%) for
C13H17NO4: C 62.14 H 6.82 N 5.57, found: C 61.76 H 6.87 N 5.62.
In the test tube (volume: 15 mL), catalyst (0.050 mmol) was
suspended in hexane (0.5 mL). Methyl ester (1.0 mmol), alcohol
(1.0 mmol), and epoxide (0.050 mmol) were added in this order.
The test tube was placed in the ChemiStation apparatus whose
temperature setting was stabilized, and magnetically stirred for
2 h under azeotropic reflux condition (heater temp: 80 °C for hex-
ane). Resulting reaction mixture was diluted with CH3CN (3 mL),
and collected in the vial. Extra CH3CN (3 mL) was used for a collec-
tion of residual chemicals in a test tube. To a combined solution
was then added measured amount of biphenyl or undecane (as
an internal standard for GC analysis), and an aliquot was used for
GC measurement. The conversion of substrate and the yield of
products were determined by GC-FID. For the isolation of product
esters, silica-gel column chromatography was carried out using
EtOAc and Hexane as eluent. The reaction setup was displayed in
Fig. S1. As some of alkylammonium salts are hydroscopic, the ini-
tial experiments are performed under N2 flow condition (Fig. S1,
right). After confirming that same results are given under an
open-air condition (Fig. S1, left), the operations were performed
under an open-air condition because of simple operation.
Hexyl 2-nitrobenzoate (3fa)
1H NMR (CDCl3, 600 MHz) d 0.89 (3 H, t like J = 7.1 Hz, ACH3),
1.30–1.34 (4 H, m, ACH2A), 1.36–1.41 (2 H, m, ACH2A), 1.69–
1.74 (2 H, m, ACH2A), 4.32 (2 H, t, J = 6.8 Hz, CH2-OCO), 7.61–
7.64 (1 H, m, ArH), 7.67 (1 H, td, J = 7.5, 1.3 Hz, ArH), 7.75 (1 H,
dd, J = 7.6, 1.5 Hz, ArH), 7.90 (1 H, dd, J = 8.0, 1.1 Hz, ArH); 13C
NMR (CDCl3, 125 MHz) d 14.0, 22.5, 25.5, 28.2, 31.3, 66.7, 123.8,
127.9, 129.9, 131.6, 132.8, 148.3, 165.5; HRMS (ESI positive, CH3-
CN): calcd for C13H17O4 + Na: 274.10498, found: 274.10132.
Hexyl 2-phenylacetate (3ga)
1H NMR (CDCl3, 600 MHz) d 0.80 (3 H, t like J = 7.0 Hz, ACH3),
1.17–1.26 (6 H, m, ACH2A), 1.50–1.55 (2 H, m, ACH2A), 3.54 (2
H, s, PhCH2A), 4.00 (2 H, t, J = 6.8 Hz, CH2AOCO), 7.17–7.26 (5 H,
d like, J = 8.9 Hz, ArH); 13C NMR (CDCl3, 125 MHz) d 13.9, 22.5,
25.5, 28.5, 31.3, 41.5, 65.0, 127.0, 128.5, 129.2, 134.2, 171.6; HRMS
(ESI positive, CH3CN): calcd for C14H20O2: 243.13555, found:
243.13752.
Characterization of isolated products
Hexyl benzoate (3aa)
Benzyl cyclohexanecarboxylate (3hb)
1H NMR (CDCl3, 600 MHz) d 0.90 (3 H, t like J = 7.1 Hz, ACH3),
1.32–1.36 (4 H, m, ACH2A), 1.42–1.48 (2 H, m, ACH2A), 1.74–
1.79 (2 H, m, ACH2A), 4.32 (2 H, t, J = 6.7 Hz, CH2AOCO), 7.42–
7.45 (2 H, m, ArH), 7.54–7.57 (1 H, m, ArH), 8.04–8.06 (2 H, m,
ArH); 13C NMR (CDCl3, 125 MHz) d 14.0, 22.5, 25.7, 28.7, 31.5,
65.1, 128.3, 129.5, 130.5, 132.8, 166.7; HRMS (ESI positive, CH3CN):
calcd for C13H18O2 + Na: 229.1199, found: 229.1232.
1H NMR (CDCl3, 600 MHz) d 1.18–1.31 (3 H, m, CyH), 1.43–1.50
(2 H, m, CyH), 1.62–1.66 (1 H, m, CyH), 1.73–1.76 (2 H, m, CyH),
1.91–1.95 (2 H, m, CyH), 2.35 (1 H, tt, J = 11, 3.6 Hz, CyH), 5.11 (2
H, s, ACH2Ph), 7.30–7.38 (5 H, m, ArH); 13C NMR (CDCl3,
125 MHz) d 25.4, 25.7, 29.0, 43.2, 65.9, 127.9, 128.0, 128.5, 136.3,
175.9; Elemental analysis calcd (%) for C14H18O2: C 77.03 H
8.31, found: C 76.72 H 8.40.
Hexyl 4-methoxybenzoate (3ba)
Benzyl pivalate (3ib)
1H NMR (CDCl3, 600 MHz) d 0.90 (3 H, t like J = 7.1 Hz, ACH3),
1.32–1.35 (4 H, m, ACH2A), 1.41–1.46 (2 H, m, ACH2A), 1.72–
1.77 (2 H, m, ACH2A), 3.86 (3 H, s, OMe), 4.28 (2 H, t, J = 6.7 Hz,
CH2AOCO), 6.92 (2 H, d like, J = 9.0 Hz, ArH), 8.00 (2 H, d like,
J = 9.0 Hz, ArH); 13C NMR (CDCl3, 125 MHz) d 14.0, 22.5, 25.7,
28.7, 31.5, 55.4, 64.8, 113.5, 123.0, 131.5, 163.2, 166.5; HRMS
(ESI positive, CH3CN): calcd for C14H20O3 + Na: 259.1305, found:
259.1273.
1H NMR (CDCl3, 600 MHz) d 1.23 (9 H, s, AC(CH3)3), 5.11 (2 H, s,
CH2Ph), 7.30–7.38 (5 H, m, ArH); 13C NMR (CDCl3, 125 MHz) d 27.2,
38.8, 66.0, 127.6, 127.9, 128.5, 136.4, 178.4; HRMS (ESI positive,
CH3CN): calcd for C12H16O2 + Na: 215.1043, found: 215.1079.
2-Hexyl benzoate (3ac)
1H NMR (CDCl3, 600 MHz) d 0.90 (3 H, t like J = 7.1 Hz, ACH3),
1.34 (3 H, d, 6.2 Hz, ACHCH3), 1.32–1.42 (4 H, m, ACH2A), 1.60–
1.64 (1 H, m, ACH2A), 1.71–1.78 (1 H, m, ACH2A), 5.16 (1 H, sextet
like, J = 6.3 Hz, CHAOCO), 7.42–7.45 (2 H, m, ArH), 7.53–7.56 (1 H,
m, ArH), 8.03–8.05 (2 H, m, ArH); 13C NMR (CDCl3, 125 MHz) d 14.0,
22.1, 25.6, 27.6, 35.8, 71.7, 128.3, 129.5, 130.9, 132.7, 166.2; HRMS
(ESI positive, CH3CN): calcd for C13H18O2 + Na: 229.1199, found:
229.1237.
Hexyl 4-methylbenzoate (3ca)
1H NMR (CDCl3, 600 MHz) d 0.90 (3 H, t like J = 7.1 Hz, ACH3),
1.32–1.35 (4 H, m, ACH2A), 1.41–1.46 (2 H, m, ACH2A), 1.73–
1.78 (2 H, m, ACH2A), 2.41 (3 H, s, Me), 4.29 (2 H, t, J = 6.7 Hz,
CH2AOCO), 7.23 (2 H, d like, J = 7.9 Hz, ArH), 7.93 (2 H, d like,
J = 8.2 Hz, ArH); 13C NMR (CDCl3, 125 MHz) d 14.0, 21.6, 22.5,
25.7, 28.7, 31.5, 64.9, 127.8, 129.0, 129.5, 143.4, 166.8; HRMS
(ESI positive, CH3CN): calcd for C8H20N4O3 + Na: 243.1428, found:
243.1391.
3-methyl-2-butenyl benzoate (3ad)
1H NMR (CDCl3, 600 MHz) d 1.77 (3 H, s, ACH3), 1.79 (3 H, s,
ACH3), 4.82 (2 H, d, J = 7.2 Hz, ACH2A), 5.48 (1 H, t sept, J = 7.2,
1.4 Hz, ACH2CH@CA), 7.40–7.45 (2 H, m, ArH), 7.51–7.55 (1 H,
m, ArH), 8.04–8.06 (2 H, m, ArH); 13C NMR (CDCl3, 125 MHz) d
18.0, 25.7, 61.8, 118.7, 128.2, 129.5, 130.5, 132.7, 139.0, 166.6;
HRMS (ESI positive, CH3CN): calcd for C12H14O2 + Na: 213.0882,
found: 213.0886.
Hexyl 4-cyanobenzoate (3da)
1H NMR (CDCl3, 600 MHz) d 0.90 (3 H, t like J = 7.1 Hz, ACH3),
1.32–1.36 (4 H, m, ACH2A), 1.41–1.46 (2 H, m, ACH2A), 1.75–
1.80 (2 H, m, ACH2A), 4.35 (2 H, t, J = 6.7 Hz, CH2AOCO), 7.74 (2
H, d like, J = 8.6 Hz, ArH), 8.14 (2 H, d like, J = 8.7 Hz, ArH); 13C
NMR (CDCl3, 125 MHz) d 14.0, 22.5, 25.6, 28.5, 31.4, 65.9, 116.2,
118.0, 130.0, 132.2, 134.3, 165.0; HRMS (ESI positive, CH3CN):
calcd for C14H17O2 + Na:254.11515, found: 254.11646.
Benzyl salicylate (3jb)
1H NMR (CDCl3, 600 MHz) d 5.39 (2 H, s, CH2Ph), 6.87 (1 H, t like,
J = 7.6 Hz, ArH), 6.99 (1 H, d like, J = 8.7 Hz, ArH), 7.35–7.47 (6 H, m,
ArH), 7.89 (1 H, dd, J = 8.0, 1.7 Hz, ArH); 13C NMR (CDCl3, 125 MHz)
d 67.0, 112.4, 117.6, 119.2, 128.3, 128.5, 128.7, 130.0, 135.3, 135.8,
161.7, 169.9; HRMS (ESI positive, CH3CN): calcd for C14H12O3
+ Na: 251.06787 found: 251.06474.
Hexyl 4-nitrobenzoate (3ea)
1H NMR (CDCl3, 600 MHz) d 0.91 (3 H, t like J = 7.1 Hz, ACH3),
1.33–1.36 (4 H, m, ACH2A), 1.42–1.47 (2 H, m, ACH2A), 1.76–
Please cite this article as: S. Tanaka, T. Nakashima, N. Satou et al., Epoxide as precatalyst for metal-free catalytic transesterification, Tetrahedron Letters,