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T. Yoshino et al. / Tetrahedron 62 (2006) 1309–1317
1
4.4.7. Ethyl 2,6-dichlorobenzoate (2g). Colorless oil; H
the starting 1-naphthoic acid disappeared. After 100 min,
the mixture was extracted with ether (5!5 mL). The
combined ether extract was purified by column chromato-
graphy on silica gel (eluent: hexane/EtOAcZ9:1) to give
pure methyl 1-naphthoate in 96% yield.
NMR (CDCl3) dZ1.42 (3H, t, JZ7.2 Hz), 4.47 (2H, q,
JZ7.2 Hz), 7.25–7.34 (3H, m); IR (neat) 2980, 1740, 1560,
1440, 1270, 1140, 1060, 800, 780 cmK1
.
4.4.8. Ethyl 3,4,5-trimethoxybenzoate (2h). Colorless
solid; mp 52 8C; 1H NMR (CDCl3) dZ1.40 (3H, t,
JZ7.2 Hz), 3.91 (3H, s), 3.92 (6H, s), 4.38 (2H, q,
JZ7.2 Hz), 7.3 (2H, s); IR (KBr) 2960, 1710, 1590, 1410,
4.4. Competitive reaction of carboxylic acids with
triethyl orthoacetate in ionic liquid
A flask containing 1-butyl-3-methylimidazolium hexa-
fluorophosphate ([bmim]PF6, 2.0 mL) as a solvent was
dried under reduced pressure with a vacuum pump for 2 h at
80 8C. Then, 3,5-dinitrobenzoic acid (1.0 mmol), palmitic
acid (1.0 mmol), and triethyl orthoacetate (1.1 mmol) were
added to the ionic liquid and the obtained mixture was
heated at 80 8C under an argon atmosphere. After 30 min,
the mixture was extracted with ether (10!5 mL). The
combined ether extract was purified by column chromato-
graphy on silica gel (eluent: hexane/EtOAcZ5:1) to give
ethyl 3,5-dinitrobenzoate (97% yield) and ethyl palmitate
(11% yield), together with palmitic acid (79% yield).
1330, 1230, 1110, 990, 760 cmK1
.
4.4.9. Ethyl pyrazinecarboxylate (2i). Colorless solid; mp
1
48–49 8C; H NMR (CDCl3) dZ1.47 (3H, t, JZ7.2 Hz),
4.53 (2H, q, JZ7.2 Hz), 8.74 (1H, dd, JZ2.4, 1.6 Hz), 8.77
(1H, d, JZ2.4 Hz), 9.33 (1H, d, JZ1.6 Hz); IR (KBr) 2980,
1740, 1370, 1310, 1280, 1160, 1120, 1020, 860, 780 cmK1
.
4.4.10. Ethyl 2,4,6-trimethylbenzoate (2j). Colorless oil;
1H NMR (CDCl3) dZ1.38 (3H, t, JZ7.2 Hz), 2.28 (3H, s),
2.29 (6H, s), 4.38 (2H, q, JZ7.2 Hz), 6.85 (2H, d,
JZ0.5 Hz); IR (neat) 2980, 1730, 1610, 1270, 1080 cmK1
.
Compounds 2a–2o, 2r–2t, 3a–3d, 8a, 8b, and 9 were
identified with commercially available authentic
compounds.
4.4.11. Ethyl 2,4,6-triisopropylbenzoate (2k). Colorless
oil; 1H NMR (CDCl3) dZ1.24 (18H, m), 1.35 (3H, t,
JZ7.2 Hz), 2.87 (3H, m), 4.36 (2H, q, JZ7.2 Hz), 7.01
(2H, s); IR (neat) 2960, 1730, 1460, 1250, 1080 cmK1
.
1
4.4.1. Ethyl 1-naphthoate (2a). Colorless oil; H NMR
(CDCl3) dZ1.47 (3H, t, JZ7.2 Hz), 4.48 (2H, q,
JZ7.2 Hz), 7.52 (2H, m), 7.62 (1H, t, JZ7.2 Hz), 7.88
(1H, d, JZ8.2 Hz), 8.02 (1H, d, JZ8.2 Hz), 8.18 (1H, dd,
JZ7.2, 1.5 Hz), 8.91 (1H, d, JZ8.2 Hz); IR (neat) 2980,
4.4.12. Ethyl triphenylacetate (2l). Colorless solid; mp
117–118 8C; 1H NMR (CDCl3) dZ1.20 (3H, t, JZ7.2 Hz),
4.28 (2H, q, JZ7.2 Hz), 7.18 (6H, m), 7.27 (9H, m); IR
(KBr) 2980, 1740, 1370, 1310, 1280, 1160, 1120, 1020, 860,
1710, 1510, 1280, 1240, 1200, 1140, 780 cmK1
.
780 cmK1
.
4.4.13. Ethyl phenylpropiolate (2m). Colorless oil; 1H
NMR (CDCl3) dZ1.36 (3H, t, JZ7.2 Hz), 4.31 (2H, q,
JZ7.2 Hz), 7.38 (2H, t, JZ7.4 Hz), 7.45 (1H, tt, JZ7.4,
1.7 Hz), 7.59 (2H, d, JZ7.4 Hz); IR (neat) 2980, 2210,
4.4.2. Ethyl 2,6-dimethoxybenzoate (2b). Colorless solid;
mp 69–70 8C; 1H NMR (CDCl3) dZ1.37 (3H, t, JZ7.2 Hz),
3.82 (6H, s), 4.39 (2H, q, JZ7.2 Hz), 6.56 (2H, d,
JZ8.4 Hz), 7.28 (1H, t, JZ8.4 Hz); IR (KBr) 2990, 1730,
1590, 1480, 1430, 1290, 1250, 1110, 1075, 780 cmK1
.
1710, 1490, 1370, 1280, 1190, 1020, 760 cmK1
.
4.4.3. Ethyl 3,5-dinitrobenzoate (2c). Yellow solid; mp
92–93 8C; H NMR (CDCl3) dZ1.48 (3H, t, JZ7.2 Hz),
4.4.14. Ethyl hippurate (2n). Colorless solid; mp
61–62 8C; H NMR (CDCl3) dZ1.32 (3H, t, JZ7.2 Hz),
1
1
4.53 (2H, q, JZ7.2 Hz), 9.18 (2H, d, JZ2.1 Hz), 9.23 (1H,
t, JZ2.1 Hz); IR (KBr) 3000, 1730, 1540, 1350, 1280,
4.27 (4H, m), 6.68 (1H, s), 7.45 (2H, t, JZ7.4 Hz), 7.53
(1H, t, JZ7.4 Hz), 7.82 (2H, d, JZ7.4 Hz); IR (KBr) 3340,
740 cmK1
.
1760, 1640, 1530, 1200 cmK1
.
4.4.4. Ethyl palmitate (2d). Colorless oil; 1H NMR
(CDCl3) dZ0.88 (3H, t, JZ6.9 Hz), 1.23–1.34 (27H, m),
1.62 (2H, quin, JZ7.5 Hz), 2.29 (2H, t, JZ7.5 Hz), 4.12
(2H, q, JZ7.2 Hz); IR (neat) 2930, 2850, 1740, 1470,
4.4.15. Ethyl oleate (2o). Colorless oil; H NMR (CDCl3)
dZ0.88 (3H, t, JZ6.8 Hz), 1.23–1.37 (23H, m), 1.62 (2H,
quin, JZ7.3 Hz), 2.01 (4H, m), 2.29 (2H, t, JZ7.6 Hz),
4.12 (2H, q, JZ7.1 Hz), 5.35 (2H, m); IR (neat) 2930, 2850,
1
1180 cmK1
.
1740, 1460, 1180 cmK1
.
4.4.5. Ethyl cyclohexanecarboxylate (2e). Colorless oil;
1H NMR (CDCl3) dZ1.17–1.34 (3H, m), 1.25 (3H, t,
JZ7.2 Hz), 1.43 (2H, qd, JZ12.3, 2.7 Hz), 1.64 (1H, m),
1.76 (2H, m), 1.90 (2H, dd, JZ12.3, 2.7 Hz), 2.28 (1H, tt,
JZ11.4, 3.6 Hz), 4.11 (2H, q, JZ7.2 Hz); IR (neat) 2930,
4.4.16. N-Benzyloxycarbonyl-L-tryptophan ethyl ester
(2p). Colorless solid; mp 85–86 8C (lit.22 mp 85–87 8C); 1H
NMR (CDCl3) dZ1.19 (3H, t, JZ7.2 Hz), 3.31 (2H, d,
JZ5.4 Hz), 4.12 (2H, m), 4.70 (1H, m), 5.10 (2H, m), 5.32
(1H, d, JZ8.0 Hz), 6.94 (1H, d, JZ2.0 Hz), 7.08 (1H, t,
JZ8.0 Hz), 7.18 (1H, t, JZ8.0 Hz), 7.33 (6H, m), 7.53 (1H,
d, JZ8.0 Hz), 8.09 (1H, s, broad); [a]2D1 C37.9 (c 1.0,
2850, 1730, 1450, 1380, 1310, 1250, 1170, 1040 cmK1
.
CHCl3); IR (KBr) 3360, 1740, 1710, 1530, 1220 cmK1
.
4.4.6. Ethyl 1-adamantanecarboxylate (2f). Colorless oil;
1H NMR (CDCl3) dZ1.24 (3H, t, JZ7.2 Hz), 1.71 (6H, t,
JZ14.5 Hz), 1.88 (6H, d, JZ2.9 Hz), 2.01 (3H, s), 4.10
(2H, q, JZ7.2 Hz); IR (neat) 2910, 1730, 1450, 1320, 1230,
4.4.17. a-D-Xylofuranuronic acid, 1,2-O-(1-methyl-
ethylidene)-3-O-(phenylmethyl)-, ethyl ester (2q). Color-
less oil; 1H NMR (CDCl3) dZ1.23 (3H, t, JZ7.2 Hz), 1.32
1180, 1080, 1030, 740 cmK1
.