M. Iinuma et al. / Tetrahedron 69 (2013) 2961e2970
2969
4.6.1. Methyl 2-phenylpropanoate (7a). Colorless oil (lit.11b oil); IR
(neat): 2982, 1738, 1454, 1208, 1167 cmꢂ1 1H NMR (500 MHz,
CDCl3):
d
¼2.52 (s, 3H), 7.20 (s, 1H), 7.29 (t, J¼7.5 Hz, 1H), 7.40 (t,
;
J¼7.6 Hz, 2H), 7.60 (d, J¼7.9 Hz, 2H); 13C NMR (125 MHz, CDCl3):
CDCl3):
d
¼1.50 (d, J¼7.2 Hz, 2H), 3.66 (s, 3H), 3.73 (q, J¼7.2 Hz, 1H),
d¼14.03, 121.83, 123.87, 128.03, 128.15, 128.78, 151.04, 160.95.
7.24e7.35 (m, 5H); 13C NMR (125 MHz, CDCl3):
d
¼18.32, 45.11,
51.54, 126.84, 127.19, 128.36, 140.34, 174.52.
4.7.2. 5-(40-Chlorophenyl)-2-methyloxazole (8b). Mp 68e70 ꢀC
(lit.7g mp: 74e75.5 ꢀC); IR (neat): 3053, 1573, 1554, 1482, 1089,
4.6.2. Methyl 2-(40-methylphenyl)propanoate (7b). Colorless oil
(lit.11b oil); IR (neat): 2951, 1738, 1205, 1165 cmꢂ1 1H NMR
(500 MHz, CDCl3):
¼1.49 (d, J¼7.2 Hz, 3H), 2.32 (s, 3H), 3.65 (s, 3H),
823 cmꢂ1
;
1H NMR (400 MHz, CDCl3):
d¼2.52 (s, 3H), 7.19 (s, 1H),
;
7.35 (d, J¼8.5 Hz, 2H), 7.51 (d, J¼8.7 Hz, 2H): 13C NMR (100 MHz,
d
CDCl3):
161.10.
d
¼13.93, 122.18, 125.24, 126.53, 128.94, 133.64, 149.98,
3.68 (q, J¼7.2 Hz, 1H), 7.13 (d, J¼8.0 Hz, 2H), 7.18 (d, J¼8.0 Hz, 2H);
13C NMR (125 MHz, CDCl3):
129.21, 136.62, 137.50, 175.00.
d
¼18.52, 20.90, 44.88, 51.82, 127.20,
4.7.3. 5-(40-Bromophenyl)-2-methyloxazole (8c). Mp 97e99 ꢀC
(lit.14 mp: 98e100 ꢀC); IR (neat): 2971, 1589, 1575, 1478, 1402, 1105,
4.6.3. Methyl 2-(40-chlorophenyl)propanoate (7c). Colorless oil
(lit.11b oil); IR (neat): 2952, 1739, 1493, 1208, 1167, 1092 cmꢂ1 1H
1067, 826, 761 cmꢂ1; 1H NMR (500 MHz, CDCl3):
d¼2.53 (s, 3H), 7.51
;
(d, J¼8.9 Hz, 2H), 7.57 (d, J¼8.9 Hz, 2H), 7.80 (s, 1H); 13C NMR
NMR (500 MHz, CDCl3):
d
¼1.47 (d, J¼7.2 Hz, 3H), 3.64 (s, 3H), 3.69
(125 MHz, CDCl3):
139.74, 161.99.
d
¼13.91, 121.64, 126.91, 130.09, 131.81, 133.33,
(q, J¼7.2 Hz, 1H), 7.22 (d, J¼8.3 Hz, 2H), 7.27 (d, J¼8.3 Hz, 2H); 13C
NMR (125 MHz, CDCl3):
132.79, 138.83, 174.31.
d¼18.33, 44.60, 51.87, 128.57, 128.73,
4.7.4. 2-Methyl-5-(40-methylphenyl)oxazole (8d). Mp 51e53 ꢀC
(lit.7g mp: 54e55 ꢀC); IR (neat): 1587, 1505, 1109, 1070, 821 cmꢂ1
;
4.6.4. Methyl 2-(40-methoxyphenyl)propanoate (7d). Colorless oil
(lit.11b oil); IR (neat): 2952, 1736, 1512, 1247, 1208, 1178 cmꢂ1 1H
NMR (500 MHz, CDCl3):
¼1.47 (d, J¼7.2 Hz, 3H), 3.65 (s, 3H), 3.67
1H NMR (500 MHz, CDCl3):
d
¼2.35 (s, 3H), 2.49 (s, 3H), 7.19 (d,
;
J¼7.7 Hz, 2H), 7.59 (d, J¼8.3 Hz, 2H), 7.74 (s,1H); 13C NMR (125 MHz,
d
CDCl3):
d¼13.9121.19, 125.22, 128.27, 129.32, 132.64, 137.61, 140.63,
(q, J¼7.2 Hz, 1H), 3.78 (s, 3H), 6.85 (d, J¼8.5 Hz, 2H), 7.22 (d,
161.61; ESI-HRMS: m/z calcd for C11H12ON [MþH]: 174.0913; found:
J¼8.5 Hz, 2H). 13C NMR (100 MHz, CDCl3):
d
¼18.32, 44.17, 51.47,
174.0913.
54.75, 113.67, 128.13, 132.34, 158.42, 174.80.
4.7.5. 2-Methyl-5-(40-nitrophenyl)oxazole (8e). Mp 157e159 ꢀC
(lit.7g mp: 161e162 ꢀC); IR (neat): 3122, 1607, 1557, 1504, 1347, 1328,
4.6.5. Methyl 2-(benzo[b]thiophen-3-yl)propanoate (7e). Colorless
oil; IR (neat): 2983, 1737, 1430, 1200, 1165, 763 cmꢂ1 1H NMR
(400 MHz, CDCl3):
¼1.63 (d, J¼7.2 Hz, 3H), 3.66 (s, 3H), 4.14 (q,
;
1132, 1105, 1059, 942, 851, 754 cmꢂ1 1H NMR (500 MHz, CDCl3):
;
d
d
¼2.58 (s, 3H), 7.42 (s, 1H), 7.76 (d, J¼9.1 Hz, 2H), 8.28 (d, J¼8.9 Hz,
J¼7.2 Hz, 1H), 7.31 (s, 1H), 7.34e7.40 (m, 2H), 7.81 (d, J¼7.9 Hz, 1H),
2H); 13C NMR (125 MHz, CDCl3):
133.86, 146.97, 149.11, 162.90.
d¼14.10, 124.20, 124.45, 125.46,
7.84 (d, J¼7.5 Hz, 1H); 13C NMR (125 MHz, CDCl3):
¼17.24, 39.01,
d
51.84, 121.49, 122.47, 122.66, 123.90, 124.17, 134.60, 137.74, 140.17,
174.05; ESI-HRMS: m/z calcd for C12H13O2S [MþH]: 221.0631;
found: 221.0627.
Acknowledgements
Financial support in the form of a Grant-in-Aid for Scientific
Research (No. 20550033) from the Ministry of Education, Culture,
Sports, Science, and Technology in Japan, and Iodine Research
Project in Chiba University is gratefully acknowledged.
4.6.6. Methyl 2-(benzofuran-2-yl)propanoate (7f). Colorless oil; IR
(neat): 2989, 1743, 1455, 1201 cmꢂ1 1H NMR (500 MHz, CDCl3):
;
d
¼1.62 (d, J¼7.5 Hz, 3H), 3.73 (s, 3H), 3.96 (q, J¼7.3 Hz, 1H), 6.57 (s,
1H), 7.20 (t, J¼7.5 Hz, 1H), 7.25 (t, J¼7.7 Hz, 1H), 7.44 (d, J¼8.0 Hz,
1H), 7.52 (d, J¼7.6 Hz, 1H); 13C NMR (100 MHz, CDCl3):
¼15.71,
d
39.76, 52.41, 103.08, 111.07, 120.72, 122.66, 123.88, 128.31, 154.71,
156.18, 172.52; ESI-HRMS: m/z calcd for C12H12O3Na [MþNa]:
227.0679; found: 227.0673.
References and notes
1. (a) Trost, B. M. Angew. Chem., Int. Ed. Engl. 1995, 34, 259; (b) Sheldon, R. A. Chem.
Ind. 1997, 12; (c) Kolb, H. C.; Finn, M. G.; Sharpless, K. B. Angew. Chem., Int. Ed.
2001, 40, 2004.
4.7. General procedure for preparation of 5-aryl-2-
methyloxazoles from acetophenones with IS-DIB A or B in
acetonitrile
2. Lawrence, N. J. J. Chem. Soc., Perkin Trans. 1 1998, 1739.
3. (a) Mancuso, A. J.; Huang, S. L.; Swern, D. J. Org. Chem. 1978, 43, 2480; (b)
Omura, K.; Swern, D. Tetrahedron 1978, 34, 1651; (c) Mancuso, A. J.; Swern, D.
Synthesis 1981, 165; (d) Tidwell, T. T. Synthesis 1990, 857; (e) Tidwell, T. T. Org.
React. 1990, 39, 297; (f) Rose, N. G. W.; Blaskovich, M. A.; Evindar, G.; Wilkinson,
S.; Luo, Y. Org. Synth. 2002, 79, 216; (g) Pichlmair, S.; Margues, M. M. B.; Green,
M. P.; Martin, H. J.; Mulzer, J. Org. Lett. 2003, 5, 4657; (h) Ahmad, N. M. In Name
Reactions for Functional Group Transformations; Li, J. J., Corey, E. J., Eds.; Wiley:
2007; p 291.
4. (a) Dess, D. B.; Martin, J. C. J. Org. Chem. 1983, 48, 4155; (b) de Lera, A. R.;
Okamura, W. H. Tetrahedron Lett. 1987, 28, 2941; (c) Holsworth, D. D. In Name
Reactions for Functional Group Transformations; Li, J. J., Corey, E. J., Eds.; Wiley:
2007; p 218.
5. (a) De Mico, A.; Margarita, R.; Parlanti, L.; Vescovi, A.; Piancatelli, G. J. Org.
Chem. 1997, 62, 6974; (b) Sakuratani, K.; Togo, H. Synthesis 2003, 21; (c) But,
T. Y. S.; Tashino, Y.; Togo, H.; Toy, P. H. Org. Biomol. Chem. 2005, 3, 970; (d)
Piancatelli, G.; Leonelli, F. Org. Synth. 2006, 83, 18; (e) Vatele, J. Tetrahedron
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J. Org. Chem. 2006, 1672; (g) Fuwa, H.; Yamaguchi, M.; Sasaki, M. Org. Lett.
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Org. Lett. 2011, 13, 6268; (h) Shimokawa, J.; Harada, T.; Yokoshima, S.;
Fukuyama, T. J. Am. Chem. Soc. 2011, 133, 17634; (i) Reddy, C. R.; Rao, N. N.;
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Guillamot, G.; Cossy, J. Eur. J. Org. Chem. 2012, 2990.
To a solution of IS-DIB A or B (1.5 equiv, 1.5 mmol) in CH3CN
(10 mL) was added TfOH (4.5 equiv, 4.5 mmol) at 0 ꢀC. The obtained
mixture was stirred for 2 h at 0 ꢀC under argon atmosphere. Then,
a solution of acetophenone (1.0 equiv, 1.0 mmol) in CH3CN (2 mL)
was added. The mixture was stirred for 5 h under refluxing con-
ditions. After the reaction, aq NaHCO3 (10 mL) was added. The
aqueous layer was extracted with Et2O (3ꢁ20 mL). The organic
layer was dried over Na2SO4, and removal of the solvent under
reduced pressure afforded 2-methyl-5-phenyloxazole, and purity
of the product was estimated by 1H NMR spectroscopy. On the
other hand, the aqueous layer was extracted with CHCl3 (3ꢁ20 mL).
Then, the organic layer was washed with aq Na2SO3 and brine, and
dried over Na2SO4. Removal of the solvent under reduced pressure
afforded ion-supported iodobenzene.
4.7.1. 2-Methyl-5-phenyloxazole (8a). Mp 55e57 ꢀC (lit.7g mp:
57e58.5 ꢀC); IR (neat): 1578, 1560, 1485 cmꢂ1; 1H NMR (500 MHz,
6. (a) Weixing, Q.; Erlei, J.; Weiliang, B.; Yongmin, Z. Angew. Chem., Int. Ed. 2005,
44, 952; (b) Weixing, Q.; Erlei, J.; Weiliang, B.; Yongmin, Z. Tetrahedron 2006, 62,