1226 Bull. Chem. Soc. Jpn., 77, No. 6 (2004)
New In Situ Preparative Formation of Diazoethane
stirring at 60 ꢂC overnight, the reaction mixture was cooled to
room temperature and filtered to remove insoluble materials. The
filtrate was concentrated in vacuo. The residue was purified by
silica-gel column chromatography (10 g). Elution with hexane–
AcOEt (7:3) afforded 12b (49 mg, 99%). Mp 35.1–35.3 ꢂC;
1H NMR (400 MHz, CDCl3) ꢁ 7.58 (m, 1H), 7.18 (dd, 1H,
J ¼ 1:0, 3.4 Hz), 6.51 (dd, 1H, J ¼ 2:0, 3.4 Hz), 4.37 (q, 2H, J ¼
7:1 Hz), 1.38 (t, 3H, J ¼ 7:1 Hz). The spectral data were identical
with those of the commercially available sample (TCI, F0098).
Ethyl (R)-2-Methoxy-2-phenylacetate (12c): 1H NMR (400
MHz, CDCl3) ꢁ 7.45 (m, 2H), 7.36 (m, 3H), 4.76 (s, 1H), 4.19
(m, 2H), 3.41 (s, 3H), 1.22 (t, 3H, J ¼ 7:1 Hz); IR (film) 2983,
2937, 2827, 1749, 1454, 1257, 1180, 1107, 1028, 731, 698
The authors express our most cordial thanks to Professor
Masatoki Ito of Department of Chemistry, Keio University,
for his direction and help on time-resolved IR measurements
and for reviewing our manuscript. We also thank Professors
Satoshi Yabushita and Tohru Yamada of the same department,
for their discussions and encouragements on IR studies. The au-
thentic specimen of 12d is indebted to Mr. Masayuki Kurokawa
and is acknowledged with thanks. This work was accomplished
as part of the 21st Century COE Program (KEIO LCC) from the
Ministry of Education, Culture, Sports, Science and Technolo-
gy, this grant is acknowledged with thanks. This work was also
supported by the collaborating program of ‘‘CREST: Creation
of Functions of New Molecules and Molecular Assemblies’’
of Japan Science and Technology Corporation, and we express
our sincere thanks to Professors Keisuke Suzuki and Takashi
Matsumoto of the Tokyo Institute of Technology. Part of this
work was supported by the ‘‘Science and Technology Program
on Molecules, Supra-Molecules and Supra-Structured Materi-
als’’ of an Academic Frontier Promotional Project and Grant-
in-Aid for Scientific Research (No. 14560084).
24
cmꢁ1; ½ꢀꢃD ꢁ97:7 (c 1.01, CHCl3). On the basis of HPLC analy-
sis, the ee was estimated to be >99:9%. HPLC [column, Chiralcel
OJ; 0.46 cm ꢄ 25 cm; hexane-2-propanol (9:1); flow rate 0.5 mL/
1
min]: tR ¼ 24:7 min for (R)-12c, 27.8 min for (S)-12c. H NMR
and IR spectra were identical with those of racemate previously
reported.24
Ethyl (S)-N-Boc-indoline-2-carboxylate (12d): Mp 62.0–
62.3 ꢂC; 1H NMR (400 MHz, CDCl3) ꢁ 7.90 (br s, 0.7H), 7.49
(br s, 0.3H), 7.20 (dd, 1H, J ¼ 7:3, 7.3 Hz), 7.11 (d, 1H, J ¼ 7:3
Hz), 6.94 (dd, 1H, J ¼ 7:3, 7.3 Hz), 4.90 (br s, 0.3H), 4.85 (br s,
0.7H), 4.21 (m, 2H), 3.51 (m, 1H), 3.10 (dd, 1H, J ¼ 3:9, 16.6
Hz), 1.59 (s, 3H), 1.50 (s, 6H), 1.27 (t, 3H, J ¼ 7:1 Hz); IR
(KBr) 2987, 1747, 1703, 1603, 1487, 1390, 1321, 1201, 1167,
750 cmꢁ1. The spectral data were identical with those of an authen-
tic sample, prepared from indolin-2-carboxylic acid via the t-bu-
toxycarbonylation and esterification with K2CO3–EtI. Elemental
analysis of the authentic specimen: Anal. Calcd for C16H21NO4:
C, 65.96; H, 7.27; N, 4.81%. Found: C, 65.88; H, 7.22; N, 4.84%.
N-Acetyl-L-phenylalanine Ethyl Ester (12e): Mp 87.4–87.9
ꢂC; 1H NMR (400 MHz, CDCl3) ꢁ 7.27 (m, 3H), 7.10 (m, 2H),
5.95 (d, 1H, J ¼ 6:3 Hz), 4.87 (m, 1H), 4.17 (q, 2H, J ¼ 7:3
Hz), 3.12 (m, 2H), 1.99 (s, 3H), 1.25 (t, 3H, J ¼ 7:3 Hz); IR
(KBr) 3317, 2972, 2933, 1732, 1645, 1533, 1377, 1346, 1223,
1200, 698 cmꢁ1. The spectral data were identical with those of
the commercially available sample (Sigma, A-4251).
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6
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Hz), 2.35 (t, 2H, J ¼ 6:3 Hz), 1.98 (tt, 2H, J ¼ 6:3, 6.3 Hz),
1.70 (s, 3H), 1.36 (t, 3H, J ¼ 6:8 Hz); IR (film) 2945, 1643,
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identical with that previously reported.25
´
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´
8
J. W. Lown and S. M. S. Chauhan, J. Org. Chem., 46, 5309
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7:0 Hz), 1.47 (t, 3H, J ¼ 7:0 Hz); IR (KBr) 2987, 1595, 1496,
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(TCI, N0216).
2,4-Dinitrophenetole (18): Mp 85.0–85.2 C; H NMR (400
MHz, CDCl3) ꢁ 8.66 (m, 1H), 8.35 (m, 1H), 7.13 (m, 1H), 4.25
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2989, 1614, 1525, 1352, 1290, 1155, 1024, 742 cmꢁ1; MS m/z
= 212 (Mþ). The spectral data were identical with those of the
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9
We omitted methyl group as the substituent in the following
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ꢂ
1
12 T. Mandai and T. Yamakawa, Synlett, 2000, 862.